I Noticed that if you have won any of the LM cars they stiill need some tweaking, but i now that the impreza LM car can tuned over 1000hp turning it into a monster!!
I personally just LOVE the S2000 LM car. Of course in black and gold (brown?)... those colors make it faster.
I was racing around in 2 player last night against a buddy (who is actually better than I am) but the S2000 isn't as heavy (or doesn't feel as heavy) as the Impreza or the FTO.
Well, if you mean the LM cars other than the "Big Three" real-life Le Mans cars, I'd have to go with the S2000, too. Recently got the blue/black one to go with my high milage red-orange/black one. I have a couple RX-7 LMs, too.