I THINK NFS underground but the game i lyk most is NFS Carbon
one has to define the parameters by which it is rating a game. i personally prefer Need For Speed: Porsche Unleashed cuz of its driving experience. one can feel the car gripping the road when accelerating out of a turn. in a front-engine Real-Wheel-Drive car, accelerating in a turn can send the car into over-steer while in a rear-engine real-wheel-drive car (read Porsche 911), the wheels grip the road. and u can feel this phenomenon in Porsche Unleashed!I love the intro to GT 1 and NFS 2!!!
There doesn't exist any game that will last long.
Technology changes and every year new game arrives in the market.
In general NEED FOR SPEED series and GRAN TURISMO series are the the best for every car enthusist.
here's one i made earlier....
What about "Project Gotham Racing 3" on Xbox 360.