Well, it depends on a lot of factors...How many miles does the car have, how well was it maintained, what engine is in it...the thing about BMW's is that you can almost pinpoint when something will need to be replaced. So as far as the cars being unreliable, it is more or less a situation of preventative maintenance...If you find the right places to look you can get parts for better prices than what the stealership will sell them to you. Generally the price of parts aren't that bad...what's killer is the labor rates to have stuff installed, and if you can prevent taking the car to shops and do stuff yourself then you should be pretty good. Luckily there is a wealth of information on these cars online with complete writeups and photos of procedures from guys who have been through the same things.
These cars deffinitely require a lot of attention. Some more than others. Like I said, it depends on the model, the year, the engine, and how many miles it has and how well it was maintained. Infact, sometimes it is better to go with a slightly higher mileage one (assuming all maintenance was taken care of) because then you can be sure a lot of the issues that occur in the first 70-100k will be taken care of.
I don't know the complexities of the STS, but BMW's are actually fairly straightforward to work on. Their engine bays are pretty accessible and aren't cluttered with wiring and whatnot. With the help of BimmerForums (the BMW forum i frequent) and the Bentley manual (the import/german equivalent to the chilton manuals I believe) I can pretty much tackle any task myself.
Now, I'd be lying if I said these cars were cheap...They can get pretty pricey and require significant attention depending on the situation. But they are very good cars that can, and usually do last a very long time. I just saw a 97 or so M3 with 213,000 miles on it going for 7 grand on auto trader...the thing looked immaculate and I'm sure it still runs great. I remember reading an article in a BMW mag of a guy who still had his e34 after 350,000 miles or so and that too was still in great shape. I believe he traded up for a 2001 M5 or something...
But yea, BMW's are enthusiasts cars for a good portion of owners. They tend to be well taken care of and proper atention has been given to them. In enthusiasts hands they will run for very long times. These aren't cars that just die on you or give up the ghost, they are solid cars. You've just got to do your homework before hand.
If you're interested in a BMW, I can point you in the right direction for information and people to talk to. If not, then that's cool too. BMW's are great cars, and for me, I feel the price to be paid for owning one is deffinitely outweighed by the total package and driving experience. They are deffinitely different cars..something about them, it is hard to explain...maybe it is that they have soul. BMW's are just one of your many choices out there though. I'm not trying to push you to get one...just throwin it out there for ya :AH-HA_wink: