Definitely Audi followed closely by Alfa-Romeo. I actually owned a 1988 Alfa-Romeo 75 2.0 with two carbs and none of that twin-spark crap and it was probably the fastest car I've ever driven. My friend has a 2003 BMW M3 but I still liked my Alfa better. Too bad the metal & paintwork was so bad that in a quiet summerday, I could almost hear it rust away.
Just one? Like if I could have any car on the planet and just that one dream car...jeez, I have no idea. I have a top 10 list, majority of them are Ferraris but there are others.
Ok, so the McLaren F1 is fast, the Ferrari Enzo is an amazing feat of technology, and the new Ford GT offers the best bang for buck. But I'm going to have to pick the 1966 Ferrari GTO. One of the rarest of the rare and a race history that car companies would kill for.
Ferrari 250 GTO
the next few are just pics from Ferrari of Washinton. btw, the red convertible in the 2nd pic; a similiar one was sold for $15mil at a Christie's auction in NY. that's a rare Ferrari 250 GT California with covered headlights, less than 100 were built (like in Ferris Bueller).