2008 BMW 3 Series 328i 2dr Convertible (3.0L 6cyl 6M)
This is nearly a great car. Fast. Handles well. Looks great. Sounds great. The retracting top is a thing of beauty. But it isn't as reliable as my old Alfa Romeo. Run flat tires are fragile; I've had to replace four of them in two years. I can deal with the somewhat harsh ride, but the huge expense and inconvenience has taught me never to buy another car with run flats. The fuel injection system broke down, taking the car out of commission for several days. Seats rattle. The cable connecting the ipod to the sound system is poor, and despite replacement still cuts out a channel from time to time. iDrive isn't that bad; lose the run flats, make it reliable, and it would be great.
The folding top. The engine. The rain-sensing wipers.
Lose the run flats. Pay attention to build quality.