Extreme Efficiency, Sport Experience

[dwightlooi]

The Chevy volt is a nice technological exercise, but in practical terms there aren’t that many people who want to spend $40K to save money on gas with a plug in vehicle. Not that many wants to pay higher taxes so government can subsidize it either. If you set aside the plug in aspects of the vehicle and just consider its IC-electric efficiency, it is not very impressive. The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve. That’s worse than the Prius (51 / 48), the Insight (40 / 43) or – in terms of the highway numbers – the Cruze Eco (42). This, quite honestly, is not that stellar.

Part of the reason for the Volt’s inefficiency operating as a strict gasoline electric hybrid that fact that it is a very heavy vehicle weighing in at close to 3800 lbs typically equipped, of which 435 lbs is the huge battery it lugs around all day. The very concept of a series hybrid is also less efficient in gasoline electric mode given that you have generation loss and motor conversion loss which – in total – is higher than if the engine drives the wheels mechanically.

So, how will you build the non-plug in vehicle with the ultimate MPG numbers?

Here’s my formula for a Cadillac or Chevrolet “Hypermiller’s Special” that is both the MPG king and at least a match for the CRX in terms of driving excitement. First, you get rid of 1200 lbs. The platform is basically an Aluminum Kappa with the engine in the trunk, battery in the nose and fuel tank in the tunnel. The body is shaped to deliver a 0.25 Cd with a boat tailed profile, full underbody tray and fenders covering the rear tires. The battery consists of 2 of the Volts’s 9 modules and packs 3.56 kWh – this is 22% the Volt’s capacity, but twice the Prius’s. Unlike most Hybrids, this one is Diesel-Electric not Gasoline Electric. This is mated to the same 55kW generator-motor in the Volt, but the 111kW main propulsion motor is ditched. This is not a CTS-V, but at 2500 lbs and 150bhp of combined diesel-electric power, it’ll hang with a Miata on the straight away or in the twisties while turning in 70MPG and comfortably seating two. It’ll have as much luggage space as a Fiero using the same arrangement of a small front compartment and a rear compartment accessed by opening the engine compartment lid.

Vehicle: Cadillac EVS

MRSP: $32,000 (before any subsidy)

Layout: Mid-Engine, Rear-Drive

Platform: Kappa Derivative MR platform

Materials: Hydroformed Aluminum Frame Rails, Aluminum Body Panels, CFRP hood and engine compartment lid

Body Style: 2-door, 2-passenger coupe; 0.25 Cd

Curb Weight: 2600 lbs

ICE: 1.0 liter DOHC 12-Valve 3-cylinder Direct Injection Turbodiesel w/ balancer shaft (based on 1.3 liter Opel CDTi engine)

ICE Output: 75 bhp @ 4000 rpm / 120 lb-ft @ 1800 rpm

Generator-Motor: 55kW Generator-Motor coupled via clutched Planetary (from Volt)

Motor-Output: 75 hp @ 65 mph; 135 lb-ft @ 0 mph

Battery: 3.56 kWh Lithium-Ion Battery Pack (two of the Volt’s nine 32-cell modules)

Wheels: 17 x 7 Light Weight Forged Aluminum

Tires: 215/45VR17 Goodyear Assurance Fuel Max

Brakes: Brembo 2-piston floating calipers 11.3” vented Discs (front), 1-piston Sliding calipers 10.4” vented discs (rear)

Fuel Type: #2 Diesel

Fuel Capacity: 8.8 Gallons

Range: 616 miles (San Francisco to Las Vegas on one tank of fuel with 7.5% reserves)

Performance: 0-60 mph in 7.5 seconds

Roadholding: 0.88 g

Fuel Economy: 70 mpg (city) / 70 mpg (hwy)

Edited August 6, 2011 by dwightlooi

[pow]

Well, first, there are more reasons to buy a Volt than to save money. It provides an excellent driving experience because of the refinement and responsiveness of its electric motor. It comes with first-rate connectivity technology, letting you check on your vehicle via smartphone app. With its LED DRLs, blacked out roof, and sharp lines, it looks great, unlike any other vehicle on the road. Not everyone judges the performance of a car based on its Nurburgring times; a vehicle's performance in the daily commute can be as important, and there, the Volt excels with its seamless and stress-free operation. Some value 0-60 times while others value MPG.

That's why I like the idea of your EVS. In terms of saving money, it also fails. Compared to a 50 MPG Prius, its payback period is ~30 years, prohibitively long for the average American driver. But it sounds like a sporty, progressive, technologically advanced, and presumably stylish two-door Cadillac, with reasons to buy one other than economic ones. Not sure if it will sell as well as the more functional, four-passenger Volt, but it's good for the Cadillac brand (it can be their hi-tech, green "halo" vehicle) and will attract new customers who would otherwise buy a BMW i3, etc.

The only thing I'm concerned about is the driving experience with a diesel-electric hybrid mated to a planetary power-split device that acts like a CVT. Part of the beauty of the Volt, Tesla Roadster, etc. is their silent operating experience, the shock you get from loads of acceleration with nary a whisper. Toyota's Hybrid Synergy Drive, no matter how powerful it is, isn't that engaging to drive and you get a lot of engine drone. I can't imagine a three-cylinder diesel @ a constant 4,000 rpm being very pleasant to listen to. Stepped gears, like you get on the M35h, help.

[dwightlooi]

The only thing I'm concerned about is the driving experience with a diesel-electric hybrid mated to a planetary power-split device that acts like a CVT. Part of the beauty of the Volt, Tesla Roadster, etc. is their silent operating experience, the shock you get from loads of acceleration with nary a whisper. Toyota's Hybrid Synergy Drive, no matter how powerful it is, isn't that engaging to drive and you get a lot of engine drone. I can't imagine a three-cylinder diesel @ a constant 4,000 rpm being very pleasant to listen to. Stepped gears, like you get on the M35h, help.

With about 3.6 kWh of battery capacity and a 75hp motor. You have about 10 miles of electric range in a 2500 lbs vehicle even if you operate the battery at between 25 and 75 % charge for longevity. What this means is that typical stop and go sessions and short city hops where you don't floor the pedal is can be entirely electric. Or at least, 3~4 times more so than a Prius with half the capacity, less motor torque and 700 lbs more weight to lug around.

The diesel is basically a cruise engine and a power adder when you floor the pedal. Neither 3-cylinders nor Diesels are that bad, especially small ones displacing 332 cc per cylinder which do not rev above 4000 rpm. The Turbo also gives the exhaust a turbine like whirl.

The same concept can be implemented at 22~24K if you forgo the aluminum frame and body shell, and drop the Caddy level interior. That's take you to about 2800 lbs and the mid to high 60s in the MPG scale and about 8 secs to 60. Still not bad.

[Drew Dowdell]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

[pow]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

You got a magic one.

[dwightlooi]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

Well, I am not saying that the Volt is a bad vehicle. What I am saying is that the Volt is a very expensive, very heavy, vehicle of mediocre performance. And, that it is that way because all the sacrifices and design choices made so it can be a short range pure electric plug-in. A vehicle that is lighter, faster, better handling and which focuses on maximizing fuel efficiency rather than being able to charge off a power grid, may be more interesting -- especially when it is $8000 to $10000 less with sportier looks and more luxurious appointments.

No, neither the Volt nor the "Hypermiler Special" make economic sense from the perspective of saving gas. You cannot save enough gas to recoup the $12000~20000 premium over a well appointed, reasonably economical Cruze LTZ. Not at $3.50 a gallon, not even at $10 a gallon. A 2-seat coupe is not as practical as a boxy, slow, 5-passenger hauler. But the very premise of expensive hybrids is NOT practical to begin with. Despite people complaining about fuel prices, the priorities of the car buying public is certainly not fuel economy at any expense or compromise -- far from it. That is why Hybrids are a niche. That is why Hybrids account for 2% of vehicle sales despite tax credits and all the cajoling by the America's Political Class. Hybrids are about being cool and feeling good about being green. And, not everyone who is looking for that type of satisfaction is of the boxy car persuasion. And, most cannot afford a Tesla roadster or Model S. A 30K Coupe with mileage to brag about, Miata like handling/performance and mid-engine good looks IS a differentiated and currently unchallenged product worth considering.

Edited August 6, 2011 by dwightlooi

[Drew Dowdell]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

You got a magic one.

No, not really. Similar results are being reported all over.

[SAmadei]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

You got a magic one.

No, not really. Similar results are being reported all over.

How hard to convert a Volt to CNG? We have a CNG station that opened nearby recently...

[pow]

"The Volt manages 35mpg city / 40 highway on its 1.4 liter engine, electric motor and whatever energy regeneration through braking it can achieve"

That is the EPA rating. In reality, the Volt is doing far far better than that. When the Volt was delivered to me there was no EV range left on the battery. I drove out to the airport and back and got 70mpg. Yes I reset the counter.

You got a magic one.

No, not really. Similar results are being reported all over.

Source?