GM expects 40% mileage boost on big SUV hybrids

[regfootball]

http://www.usatoday.com/money/autos/2007-0...m-hybrids_N.htm

General Motors (GM) said Tuesday that it now expects 40% better fuel economy in city driving from the gasoline-electric hybrid versions of its full-size SUVs than their gasoline-only counterparts, giving the hybrid Chevrolet Tahoes and GMC Yukons 19 or 20 miles a gallon in stop-and-go driving.

That's up from earlier forecasts of a 25% improvement and would give the big SUVs better mileage than some mid- and full-size, gasoline-power family sedans. It also would be better than so-called crossover SUVs that are stealing sales from truck-based SUVs such as Tahoe because crossovers typically use less fuel.

KILLER!!!!!!!!!!

Edited July 26, 2007 by regfootball

[toesuf94]

Game - set - match. I hope they do not suffer on the highway like the other hybrids do.

I am seriously in the market for one of these. I love the lack of a roof rack on the roof and the aero package on the Hybrid. I have been thinking about this truck since they were announced, and cannot wait to get one.

[gm4life]

Keep in mind these babies get the well needed 6spd. automatics. Eat that Toyota, good fuel economy from the vehicles that need it the most. Good idea. I want a Silverado version and Suburban one to pop up soon.

[CaddyXLR-V]

Are there any plans for hybrid Lambdas? If they could get 30mpg out of a full size SUV, that would be a huge marketing point.

[haypops]

Are there any plans for hybrid Lambdas?

From the article

GM will offer it next year on Cadillac Escalade, then on Chevy and GMC full-size pickups. Saturn models will get a version later.

I assume that this would be the Saturn Lambda?

[Windy-57]

Game - set - match. I hope they do not suffer on the highway like the other hybrids do.

They shouldn't suffer on the highway like others do, that's the whole point of dual-stage. These will mostly run on 4 cylinders while cruising and be able to instantly transfer back to 8 when going up hill or passing.

I assume that this would be the Saturn Lambda?

I've heard a lot of rumblings about this and other platforms. A little bit of speculation, but the feel I get is that GM is going to put them on the 900s and Lambda and see how they sell and then decide on other structures. With that in mind, I've heard loose information about dual-stage versions of Zeta, GMT360 replacement and even Theta.

[hyperv6]

I just hope this is a real world driving 40% gain and not a Prius gain.

Toyota has gotten a free pass on the Prius milage as most owners never get the high milage due to the fact you have to feather the pedal.

If GM can get 40% gain and dive it like a truck should be driven this will be great. But if GM comes up short on milage the press will ream them unlike the pass Toyota got.

[Camino LS6]

Don't forget that the mileage gain decreases with the size of the vehicle the technology is applied to. Kudos to GM for putting it where it will do the most good first.

[pow]

I just hope this is a real world driving 40% gain and not a Prius gain.

Toyota has gotten a free pass on the Prius milage as most owners never get the high milage due to the fact you have to feather the pedal.

If GM can get 40% gain and dive it like a truck should be driven this will be great. But if GM comes up short on milage the press will ream them unlike the pass Toyota got.

The "real-world" gains for the Prius are 40%. It's just that the old-EPA gain for the Prius was 100%.

[pow]

20 MPG makes it on par with the LS600hL!

Imagine an Escalade Hybrid that "gets better fuel economy than any full-size luxury vehicle."

[CaddyXLR-V]

20 MPG makes it on par with the LS600hL!

Imagine an Escalade Hybrid that "gets better fuel economy than any full-size luxury vehicle."

Especially when the Escalade has as much power, is a bigger vehicle, and is much less aerodynamic. Not to mention will cost thousands less.

[Derek77]

Keep in mind these babies get the well needed 6spd. automatics. Eat that Toyota, good fuel economy from the vehicles that need it the most. Good idea. I want a Silverado version and Suburban one to pop up soon.

I'm not sure these are 6-speeds. I'm almost positive they are 4s.

[Drew Dowdell]

I'm not sure these are 6-speeds. I'm almost positive they are 4s.

The 6speed is part of the 2 mode hybrid package

[Derek77]

The 6speed is part of the 2 mode hybrid package

You mean 4 fixed gears plus the 2 modes?

GM to Introduce Two-Mode Hybrid Suvs for 2008 Model Year

[hyperv6]

The "real-world" gains for the Prius are 40%. It's just that the old-EPA gain for the Prius was 100%.

What I am saying is the claimed high mileage that Toyota still calims and if you drive the Prius as a normaL car you only see 32 MPG VS their 40+ MPG claim.

We had a reporter here in town that did a story on the Prius she owned and how it only delivers if you feather the gas and hold up traffic.

These same problems of less than promised milage is seconded by two other owners I know. The Fact is the Prius is not the high milage champ it claioms to be if driven like a normal car.

It is important under most normal conditions that GM delivers the MPG as promised. I know GM is good on thier word on HP in most of thier new cars unlike many other companies I just hope they do the same and only prommise the milage most really will see. If it gets more all the better.

Under promise and over deliver and no one ever complains.

Edited July 27, 2007 by hyperv6

[haypops]

What I am saying is the claimed high mileage that Toyota still calims and if you drive the Prius as a normaL car you only see 32 MPG VS their 40+ MPG claim.

Whatever the real world Prius mileage is, it's important to compare it to some small 1.5 l sedan like the Echo or perhaps the even larger more powerful Corolla, not the Camry or other larger more fuel thirsty car. Slap some low rolling resistance tires on an old Echo and you got a good comparison.

[Newbiewar]

You mean 4 fixed gears plus the 2 modes?

GM to Introduce Two-Mode Hybrid Suvs for 2008 Model Year

umm... its a weapon later on down the road...

if 40% is possible with this powertrain and the 6 speed is capable of another 5-15% increase depending on application... GM will be able to see some major gains in fuel ecconomy...

but if u think about it... if GM is marketing the hybrid expense at 10k... is it really worth it... maybe....

but gm will sell some, and make a killing i think

[regfootball]

lambda hybrid would be a great people mover solution.

[Newbiewar]

lambda hybrid would be a great people mover solution.

i keep asking if lambda is capable of replacing the chevy uplander... that way it is a different style of vehicle... yet it still uses the same archatecture

and if it got 40% gains too...

you know if those gains are seen in the big vehicles... thats the bare minimum of the system...

[pow]

What I am saying is the claimed high mileage that Toyota still calims and if you drive the Prius as a normaL car you only see 32 MPG VS their 40+ MPG claim.

We had a reporter here in town that did a story on the Prius she owned and how it only delivers if you feather the gas and hold up traffic.

These same problems of less than promised milage is seconded by two other owners I know. The Fact is the Prius is not the high milage champ it claioms to be if driven like a normal car.

It is important under most normal conditions that GM delivers the MPG as promised. I know GM is good on thier word on HP in most of thier new cars unlike many other companies I just hope they do the same and only prommise the milage most really will see. If it gets more all the better.

Under promise and over deliver and no one ever complains.

The 2008 procedures more accurately reflect real-world economy, whether it's for Toyota or GM. The '08 estimates for the Prius are 48/45, which coincide with the reported averages at fueleconomy.gov, greenhybrid.com, and countless magazine long-term tests.

[Derek77]

umm... its a weapon later on down the road...

if 40% is possible with this powertrain and the 6 speed is capable of another 5-15% increase depending on application... GM will be able to see some major gains in fuel ecconomy...

but if u think about it... if GM is marketing the hybrid expense at 10k... is it really worth it... maybe....

but gm will sell some, and make a killing i think

What is a weapon later on down the road?

Is the 2-mode a 4 speed? That's what I want to know. Someone said its a 6speed. I thought my link proved they were 4 speeds. What am I missing?

[Derek77]

And about the Saturn 2-mode model. Isn't it the VUE? I recall GM saying it would be the first with the FWD 2-mode transmission.

[smk4565]

That is good news, a 40% gain is probably need to get people to keep buying big trucks. Even with a 40% gain and 20 mpg , I think a lot of people will still opt for smaller like the Highlander, and CRV and Escape, unless they absolutely need 7-8 seats and towing ability. Oil just went over $77 a barrel, gas mileage is so important now to most buyers. The Lambdas are still really big and heavy, the Edge, Escape and CRV seem to be what are hot.

I'd like to see the 2 mode on some smaller vehicles where they can really maximize economy and make some 30 and 40 mpg cars. Perhaps even 50 mpg. Just building a 50 mpg car helps image, look at the Prius, which is one of 3 Toyotas in the top 8 in sales.

[haypops]

quick explanation of two mode system

4speed automatic + 2ECVT modes + 2 60 kw motors + 300 volt battery pack

[Newbiewar]

What is a weapon later on down the road?

Is the 2-mode a 4 speed? That's what I want to know. Someone said its a 6speed. I thought my link proved they were 4 speeds. What am I missing?

if it is indeed a 4 speed... adding a six speed a couple years down the road will provide it additional ecconomy...

[GXT]

Game - set - match. I hope they do not suffer on the highway like the other hybrids do.

Nice gains, but $10K (or whatever GM subsidizes it to) will keep this from being popular until the prices comes down.

FYI, hybrids don't "suffer" on the highway. They offer very good fuel economy on the highway as they have smaller gas engines. They simply don't get the huge increases like they do in the city.

That being said, from my (very limited) understanding of the two-mode system there is a chance of some sustained electronic assist at highway speeds that is not possible with Toyota/Honda's system. This is because the two-mode can generate electricity (i.e. without having to brake). What will be interesting to see is if the two-modes have artificially high EPA highway numbers as a result. This will be a danger if it can travel quite some time on electricity without having to generate any. Personally, I would find it strangely amusing to hear about two-mode hybrids that get 35 MPG highway, yet are derided as "useless" and "a scam" because their EPA rating is 50MPG.

[pow]

Nice gains, but $10K (or whatever GM subsidizes it to) will keep this from being popular until the prices comes down.

FYI, hybrids don't "suffer" on the highway. They offer very good fuel economy on the highway as they have smaller gas engines. They simply don't get the huge increases like they do in the city.

That being said, from my (very limited) understanding of the two-mode system there is a chance of some sustained electronic assist at highway speeds that is not possible with Toyota/Honda's system. This is because the two-mode can generate electricity (i.e. without having to brake). What will be interesting to see is if the two-modes have artificially high EPA highway numbers as a result. This will be a danger if it can travel quite some time on electricity without having to generate any. Personally, I would find it strangely amusing to hear about two-mode hybrids that get 35 MPG highway, yet are derided as "useless" and "a scam" because their EPA rating is 50MPG.

The 2008 procedures more accurately reflect real-world economy, whether it's for Toyota or GM.

[PurdueGuy]

And about the Saturn 2-mode model. Isn't it the VUE? I recall GM saying it would be the first with the FWD 2-mode transmission.

You are correct - they've already stated that there will be a 2-mode Vue, with a plug-in 2-mode Vue to follow. Wouldn't surprise me one bit if they get it in the Lambda too, though.

[haypops]

quite positive review here

US today says the hybrid is nicer than the gas model and that it won't be the most expensive model either.

[Derek77]

The USA Today article was very informative. I'm glad GM is thinking of changing the regular Tahoe and Yukon with the weight saving parts of the hybrids. That's a smart move and a good way to increase legroom in the second row.

[ketch]

Hey Toyota, look over you shoulder!

[GXT]

The 2008 procedures more accurately reflect real-world economy, whether it's for Toyota or GM.

The two-mode and Toyota hybrids operate differently. While I don't know enough about the two systems to know if it will be the case, the EPA tests may react differently to them.

[JM9777]

Let's try this again (hopefully) for a final time.

The 2-Mode Hybrid is NOT a 4-speed automatic. The system behaves as a continuously variable transmission. When you accelerate, power is routed through the electric motors and the vehicle behaves as any other hybrid vehicle does. From what I understand, the 4 speeds that everyone seems to get caught up on refer to are fixed gear ratios that the system can use when cruising (mostly at highway speeds). These fixed ratios route power to the wheels through a direct mechanical path, which is more efficient than routing power through the electric motors (as the 2-Mode does at lower speeds, and as all other hybrids do 100% of the time). This is one way that the 2-Mode System provides superior highway fuel economy compared to other hybrid systems.

The system does not behave like a conventional automatic transmission. GM's explanation of it on that link is very poor, but I suppose they are trying to make it easier to understand for the average person. There is not necessarily any fuel economy advantage to be gained by adding more of these fixed ratios. It's time to stop the spread of the myth that this is somehow a 4-speed automatic. It behaves like a CVT.

Edited July 28, 2007 by JM9777

[Derek77]

Let's try this again (hopefully) for a final time.

The 2-Mode Hybrid is NOT a 4-speed automatic. The system behaves as a continuously variable transmission. When you accelerate, power is routed through the electric motors and the vehicle behaves as any other hybrid vehicle does. From what I understand, the 4 speeds that everyone seems to get caught up on refer to are fixed gear ratios that the system can use when cruising (mostly at highway speeds). These fixed ratios route power to the wheels through a direct mechanical path, which is more efficient than routing power through the electric motors (as the 2-Mode does at lower speeds, and as all other hybrids do 100% of the time). This is one way that the 2-Mode System provides superior highway fuel economy compared to other hybrid systems.

The system does not behave like a conventional automatic transmission. GM's explanation of it on that link is very poor, but I suppose they are trying to make it easier to understand for the average person. There is not necessarily any fuel economy advantage to be gained by adding more of these fixed ratios. It's time to stop the spread of the myth that this is somehow a 4-speed automatic. It behaves like a CVT.

Man, you've got to post a link or something to prove it's not a 4-speed automatic. Everything GM puts out says it a 4-speed combined with 2 electric motors. You just can't say "from what I understand.." I need proof.

[Newbiewar]

Man, you've got to post a link or something to prove it's not a 4-speed automatic. Everything GM puts out says it a 4-speed combined with 2 electric motors. You just can't say "from what I understand.." I need proof.

GM to Introduce Two-Mode Hybrid Suvs for 2008 Model Year

GM, DaimlerChrysler and BMW Group have teamed up to co-develop the world’s first two-mode hybrid system for passenger vehicles to more rapidly advance the state of hybrid technology in the industry.

The two-mode hybrid system has been established as the starting point for the GM, DaimlerChrysler and BMW Group collaboration. The two-mode system will be used for applications in GM, Chrysler Group, Mercedes Car Group, and BMW Group vehicles. Variants planned include rear, front, and all-wheel drive versions for cars, trucks and other vehicles.

The two-mode hybrid will be launched in 2007 in two of GM’s most popular full-size SUVs – the 2008 Chevrolet Tahoe and the 2008 GMC Yukon. When combined with Active Fuel Management, the two-mode hybrid is expected to enable the SUVs to deliver a composite (city and highway mpg) fuel economy improvement of 25 percent. It is also scheduled to come out in 2008 on the Cadillac Escalade as well as the Chevrolet Silverado and GMC Sierra crewcab pickup trucks. Using this system on full-size SUVs and pickups is part of GM’s strategy to apply advanced technologies on high-volume, higher fuel-consuming vehicle segments first.

The system uses two electrically continuously variable transmission (ECVT) modes of operation that optimize power and torque for various conditions. The addition of the second mode to the drive system improves efficiency and reduces the need for large electric motors, which are used in single-mode systems. The smaller motors are lighter and more easily packaged in the space of a typical automatic transmission. The ECVT modes are combined with four fixed gear ratios for high efficiency and power handling capabilities in a broad variety of vehicle applications. The combination of the two ECVT modes and four fixed gear ratios allows for efficient operation throughout a vehicle’s operating range, at low and high speeds. Also, a sophisticated electronic control module constantly optimizes the entire hybrid powertrain system to select the most efficient operation point for the power level demanded by the driver.

[Derek77]

GM to Introduce Two-Mode Hybrid Suvs for 2008 Model Year

GM, DaimlerChrysler and BMW Group have teamed up to co-develop the world’s first two-mode hybrid system for passenger vehicles to more rapidly advance the state of hybrid technology in the industry.

The two-mode hybrid system has been established as the starting point for the GM, DaimlerChrysler and BMW Group collaboration. The two-mode system will be used for applications in GM, Chrysler Group, Mercedes Car Group, and BMW Group vehicles. Variants planned include rear, front, and all-wheel drive versions for cars, trucks and other vehicles.

The two-mode hybrid will be launched in 2007 in two of GM’s most popular full-size SUVs – the 2008 Chevrolet Tahoe and the 2008 GMC Yukon. When combined with Active Fuel Management, the two-mode hybrid is expected to enable the SUVs to deliver a composite (city and highway mpg) fuel economy improvement of 25 percent. It is also scheduled to come out in 2008 on the Cadillac Escalade as well as the Chevrolet Silverado and GMC Sierra crewcab pickup trucks. Using this system on full-size SUVs and pickups is part of GM’s strategy to apply advanced technologies on high-volume, higher fuel-consuming vehicle segments first.

The system uses two electrically continuously variable transmission (ECVT) modes of operation that optimize power and torque for various conditions. The addition of the second mode to the drive system improves efficiency and reduces the need for large electric motors, which are used in single-mode systems. The smaller motors are lighter and more easily packaged in the space of a typical automatic transmission. The ECVT modes are combined with four fixed gear ratios for high efficiency and power handling capabilities in a broad variety of vehicle applications. The combination of the two ECVT modes and four fixed gear ratios allows for efficient operation throughout a vehicle’s operating range, at low and high speeds. Also, a sophisticated electronic control module constantly optimizes the entire hybrid powertrain system to select the most efficient operation point for the power level demanded by the driver.

Didn't that just prove MY point? It's not a CVT and it's not a 6-speed. It has 2 electrically continuously variable transmission modes combined, or 2 modes, or 2 electric motors, with 4 fixed gears. And what electric motor isn't variable. My RC cars as a kid were variable. If it sounds like I'm fixed on the 4 fixed gears part, I am! Why does GM keep saying in all their releases that it has 4 fixed gears or uses a conventional four-speed automatic transmission combined with two electrically variable transmission modes of operation if its not a 4-speed. Its a 4 speed with, yes, 2 electrically continuously variable modes.

[Newbiewar]

this was what was supposed to be designed...

Official Press Release (via DaimlerChrysler)

GM, DaimlerChrysler, BMW Premiere Unprecedented Hybrid Technology

Vienna, Apr 27, 2006

The state-of-the-art full hybrid system, whose components are being co-developed by General Motors Corp., DaimlerChrysler and the BMW Group for production beginning next year, represents a major automotive industry milestone due to the unprecedented fully integrated combination of electric motors with a fixed-gear transmission.

As a result of its low- and high-speed electric continuously variable transmission (ECVT) modes, the system is commonly referred to as the 2-mode hybrid. However, the sophisticated fuel-saving system also incorporates four fixed gear ratios for high efficiency and power-handling capabilities in a broad variety of vehicle applications. During the two ECVT modes and four fixed gear operations, the hybrid system can use the electric motors for boosting and regenerative braking.

In summary, the four fixed gears overlay two ECVT modes for a total of six operating functions:

Input-split ECVT mode, or continuously variable Mode 1, operates from vehicle launch through the second fixed gear ratio.

Compound-split ECVT mode, or continuously variable Mode 2, operates after the second fixed gear ratio.

First fixed-gear ratio with both electric motors available to boost the internal combustion engine or capture and store energy from regenerative braking, deceleration and coasting.

Second fixed-gear ratio with one electric motor available for boost/braking,

Third fixed-gear ratio with two electric motors available for boost/braking.

Fourth fixed-gear ratio with one electric motor available for boost/braking.

The result is trend-setting hybrid technology that provides superior fuel economy, performance and load carrying capability.

The full hybrid system being co-developed by General Motors, DaimlerChrysler and the BMW Group has an overall mechanical content and size similar to a conventional automatic transmission, yet this full hybrid transmission can operate in infinitely variable gear ratios or one of the four fixed-gear ratios.

A sophisticated electronic control module constantly optimizes the entire hybrid powertrain system to select the most efficient operation point for the power level demanded by the driver.

Key Advantages

When compared to conventional hybrid systems, this avant-garde hybrid technology, relying on both the ECVT modes and the four fixed gear ratios, provides advantages in combined (city and highway) fuel economy, dynamics and towing capability.

Traditional hybrid systems typically have only one torque-splitting arrangement and no fixed mechanical ratios. These systems are often called “one-mode” hybrids. Due to their less capable mechanical content, one-mode hybrids need to transmit a significant amount of power through an electrical path that is 20 percent less efficient than a mechanical path. This requires usually substantial compromise in vehicle capability or reliance on larger electrical motors, which can create cost, weight and packaging issues.

General Motors, DaimlerChrysler and the BMW Group have conceived a full hybrid system featuring four fixed mechanical ratios, within the two ECVT modes, to reduce power transmission through the less efficient electrical path. Consequently, the electric motors are more compact and less dependent on engine size.

This combination of two ECVT modes and four fixed gear ratios eliminates the drawbacks of one-mode hybrid systems to allow for efficient operation throughout a vehicle’s operating range, at low and high speeds. It also allows for application across a broader variety of vehicles. It is particularly beneficial in demanding applications that require larger engines, such as towing, hill climbing or carrying heavy loads.

Existing internal combustion engines can be used with relatively minimal alteration because the full hybrid system imposes no significant limitation on the size or type of engine. It enables the three global automakers to package internal combustion engines with the full hybrid transmissions more cost-effectively and offer the fuel-saving technology across a wider range of vehicles.

Initial applications are suitable for front-engine, rear- and four-wheel-drive vehicle architectures, but the full hybrid system has the flexibility to be used in front-engine, front-wheel-drive architectures in the future as well.

this is what edmunds says...

What Is It?

2008 Chevrolet Tahoe Hybrid & GMC Yukon Hybrid

What's Special About It?

Hybrids are fuel-efficient, sometimes even fast, but rugged enough to take on an off-road trail? Not with all those expensive batteries onboard.

General Motors plans to destroy this myth sometime in 2007 when the 2008 Chevrolet Tahoe Hybrid and GMC Yukon Hybrid come to market. They may be part-electric, but these are real SUVs. You can even get them with four-wheel drive and a low-range transfer case. Not your thing? No problem, order up eight-passenger seating and two-wheel drive. "Basically," says Mark LaNeve, VP of sales, service and marketing for GM North America, "you can get them any way you want."

Originally developed for GM's mass-transit buses, the Tahoe/Yukon "two-mode" hybrid system pairs two electric motors with one of GM's Vortec V8 engines. Company officials didn't want to tell us the V8's displacement, but they did say the engine's compression ratio is up from 9.9-to-1 to 12-to-1.

The first of the hybrid system's two modes covers low-speed, light-duty driving, and allows for electric propulsion only, gas engine propulsion only, or any combination of the two.

The second mode comes into play during high-speed driving or when pulling heavy loads. In this mode, the gas engine is almost always active with the electric motor providing assist when necessary. To save fuel, the V8 employs cylinder deactivation (GM's Active Fuel Management), variable camshaft phasing and late intake valve closure when operating in this mode. An onboard computer allows for synchronous shifts between modes with no interruption in power.

GM calls the Tahoe/Yukon Hybrid's transmission an electronically variable transmission, which has no fixed gear ratios as in a conventional automatic, nor any belts and pulleys as in a CVT. GM says this hybrid system promises to improve fuel economy 25 percent. That means a Tahoe Hybrid would average about 22.7 mpg.

What's Edmunds' Take?

Almost 23 mpg in a vehicle that seats eight and can tow up to 6,000 pounds? Hybrid technology may well save big SUVs from extinction. — Erin Riches

But i cant find anything to actually state the current powertrain status...

[rueben44]

WOW it is a continuously variable transmission not a 4 speed. LMAO he explained it perfect. The fixed ratios are for highway driving and it is not like a regular transmission. As he stated that is why it gets better highway mileage unlike a lot of other hybrids.

Maybe this will help:

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuous

continuous

continuous

Edited July 29, 2007 by rueben44

[Newbiewar]

WOW it is a continuously variable transmission not a 4 speed. LMAO he explained it perfect. The fixed ratios are for highway driving and it is not like a regular transmission. As he stated that is why it gets better highway mileage unlike a lot of other hybrids.

Maybe this will help:

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuous

continuous

continuous

maybe this will help...

CVT by definition

The continuously variable transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios.

The continuously variable transmission should not be confused with the power split transmission (PST), as used in the Toyota Prius and other hybrid vehicles that use two or more inputs with one output, despite some similarities in their function.

A CVT need not be automatic, nor include zero or reverse output. Such features may be adapted to CVTs in certain specific applications.

Other mechanical transmissions only allow a few different discrete gear ratios to be selected, but the continuously variable transmission essentially has an infinite number of ratios available within a finite range, so it enables the relationship between the speed of a vehicle engine and the driven speed of the wheels to be selected within a continuous range. This can provide better fuel economy than other transmissions by enabling the engine to run at its most efficient speeds within a narrow range.

CVTs have been refined over the years and are much improved from their origins.

or if that source isnt good enough to define a CVT we should goto another

CVT Basics

Unlike traditional automatic transmissions, continuously variable transmissions don't have a gearbox with a set number of gears, which means they don't have interlocking toothed wheels. The most common type of CVT operates on an ingenious pulley system that allows an infinite variability between highest and lowest gears with no discrete steps or shifts.

If you're wondering why the word "gear" still appears in the explanation of a CVT, remember that, broadly speaking, a gear refers to a ratio of engine shaft speed to driveshaft speed. Although CVTs change this ratio without using a set of planetary gears, they are still described as having low and high "gears" for the sake of convention.

but... in no means would you describe a CVT to have 4 gears...

but... an Electrical CVT... as defined by GM DCX and BMW

The state-of-the-art full hybrid system, whose components are being co-developed by General Motors Corp., DaimlerChrysler and the BMW Group for production beginning next year, represents a major automotive industry milestone due to the unprecedented fully integrated combination of electric motors with a fixed-gear transmission.

As a result of its low- and high-speed electric continuously variable transmission (ECVT) modes, the system is commonly referred to as the 2-mode hybrid. However, the sophisticated fuel-saving system also incorporates four fixed gear ratios for high efficiency and power-handling capabilities in a broad variety of vehicle applications. During the two ECVT modes and four fixed gear operations, the hybrid system can use the electric motors for boosting and regenerative braking.

[Derek77]

WOW it is a continuously variable transmission not a 4 speed. LMAO he explained it perfect. The fixed ratios are for highway driving and it is not like a regular transmission. As he stated that is why it gets better highway mileage unlike a lot of other hybrids.

Maybe this will help:

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuously variable transmission

continuous

continuous

continuous

IT'S STILL A 4-SPEED!! Not 6 as someone said earlier. And saying it has 4-speeds doesn't mean its a 4L60 either. It's also not a straight out CVT. All the links and articles prove that.

[Drew Dowdell]

IT'S STILL A 4-SPEED!! Not 6 as someone said earlier. And saying it has 4-speeds doesn't mean its a 4L60 either. It's also not a straight out CVT. All the links and articles prove that.

OMG get off it! Sorry I was wrong. I take it back! Drop it already!

You're right

You're right

You're right

mountain > molehill

[Newbiewar]

OMG get off it! Sorry I was wrong. I take it back! Drop it already!

You're right

You're right

You're right

mountain > molehill

your not totally wrong... but heres the break down of how the tranmission opperates

Input-split ECVT mode, or continuously variable Mode 1, operates from vehicle launch through the second fixed gear ratio.

Compound-split ECVT mode, or continuously variable Mode 2, operates after the second fixed gear ratio.

First fixed-gear ratio with both electric motors available to boost the internal combustion engine or capture and store energy from regenerative braking, deceleration and coasting.

Second fixed-gear ratio with one electric motor available for boost/braking,

Third fixed-gear ratio with two electric motors available for boost/braking.

Fourth fixed-gear ratio with one electric motor available for boost/braking.

[loki]

i saw an article about this, they're using the 6.0L because it's aluminum and not the 5.3L. that's what i read.

330ish HP and 360ish Lbft.

[Newbiewar]

i saw an article about this, they're using the 6.0L because it's aluminum and not the 5.3L. that's what i read.

330ish HP and 360ish Lbft.

did u read the part about the compression ratio going from 9.9 to 12.0?

[loki]

did u read the part about the compression ratio going from 9.9 to 12.0?

i saw that at the start of this article. i saw the 6.0L engine choice in a newspaper, st louis post i think. read it 1-2 days ago at a hotel... was on trip so i didn't keep the paper

[Drew Dowdell]

i saw an article about this, they're using the 6.0L because it's aluminum and not the 5.3L. that's what i read.

330ish HP and 360ish Lbft.

why does aluminum have anything to do with it?

[haypops]

why does aluminum have anything to do with it?

I assume less weight? That US Today article claims they hollowed out the front seats to save weight.

[Newbiewar]

why does aluminum have anything to do with it?

well like they learned with the LT1 and LS1, alluminum helps cool things down expecially if ur going to put compression up to 12:1

alluminum means lighter weight, faster coolings radiator...

but most likely has to do with heat from compression ratio...

just like the reverse cooling system was designed to allow the LT1 to have high compression with a good cooling system... dont think it was the greatest cooling system but it worked...

[The O.C.]

What I am saying is the claimed high mileage that Toyota still calims and if you drive the Prius as a normaL car you only see 32 MPG VS their 40+ MPG claim.

We had a reporter here in town that did a story on the Prius she owned and how it only delivers if you feather the gas and hold up traffic.

These same problems of less than promised milage is seconded by two other owners I know. The Fact is the Prius is not the high milage champ it claioms to be if driven like a normal car.

It is important under most normal conditions that GM delivers the MPG as promised. I know GM is good on thier word on HP in most of thier new cars unlike many other companies I just hope they do the same and only prommise the milage most really will see. If it gets more all the better.

Under promise and over deliver and no one ever complains.

You are about ten mpg off......the original EPA claims were like 60/50.....with most people averaging low 40's in real-world driving. (That's where the original bitch came from.) I even think that's what the buff magazines got on their long-term tests of the Prius.....low 40's.....and they certainly don't "feather" the throttle of their test vehicles.

[meekin111]

This i fantastic news although I am still sceptical of gettign a 40% improvement in real world driving conditions. A hybrid system for lambda would be excellent, high volume from four brands and great fuel economy. I would also like to see zeta hybrids with a DOHC 2.8L V6.