I've tuned a few cars for Top Gear, and a few cars spring to mind.
Obviously the Dodge Viper ACR, which is a personal favourite of mine when everyone is in the fastest cars.
Also, there is the Cadillac Cien which is a very good drag car there.
I find, the best thing to do is go for a relatively quick start, maybe 0-60 MPH in 2.5 seconds, but really go for the top speed, and try to reach 215 MPH or higher by the time you hit the wall. That's where my Viper is, and I've won a lot in it.