I enjoy driving the the '05 Subaru WRX STI. I have a '03 WRX and love Subies. Second though is the '76 Ferrari 512BB. Great car, I just wish I could upgrade it to a 6 speed.
BMW M3 but it seems to perform poorly in the game and I hate that. But I do know a big part of that reason is the driver, which is me.......Im workin on it though
Right now I'm really loving the regular Clio V6. I've got it geared so it can't exceed ~140mph. I've taken all the weight out, added no power, and tweaked the suspension just a bit.
Its not the fastest thing, but I'm constantly working to drive it. Its very involving IMHO. It brakes phenomenally and geared well beyond rationality as it is I don't go more than 2 or 3 seconds without shifting.
My favorite car on GT5 Prologue right now is a blue, Aston Martin DB9, sure it isn't the fastest or lightest car out there, but I love how the car handles when I drift with it! Another reason is the fact that very few, if any, drift or race this beautiful car online, I like to stand out from the crowd.