Mine is Need for Speed: High Stakes! :)

You gotta be shitting me! I was seriously just about to post that title thinking "No one else will pick this one!"

You do mean the original High Stakes right? Was there just the one? If so it's that one that hands down takes the cake for me.

ooh, that's an difficult one. Since there is so many, ah f*%k it, I'll list them all

1) The Duel: Test Drive 2 - with all the expansion packs
2) Street Rod
3) Need For Speed II SE
4) Need For Speed: High Stakes (1999)
5) Nascar Racing 2
6) NFS Most Wanted (2005)
7) Race Driver Grid
8) Gran Turismo 2
9) Re-Volt
10) Monster Truck Madness

I'll stop at 10 :P

Gran Turismo 1 & 2, I'm being greedy I know but how can I pick a favourite. Still great games I go back to, the mix of simulation, management, tweaking and thrill of winning using a used car with four burnt out wheels and smoking engine that just creeps over the line in time is unrivaled.

Need For Speed: Underground
Need For Speed: Underground 2
I've always liked these for the customization and very nice keyboard controls.

Need For Speed: Special Edition
Got this one as a Christmas present, the car porn video's were amazing. I was also very thankful the version I had didn't include that smack talking wanker.

Rock 'n Roll Racing!

NFS Underground, but I didn't play many others. However I liked the customizing of the the car and driving really fast in an urban area.

F-Zero GX by far.

I always look forward to the public service announcements put on to the intros of those games. Why don't other games have those, like Postal or Carmageddon. :P

Night Driver - I loved this game

Forza 4 and prior to that Forza 3!

As a more arcade racer I'd like Test Drive Unlimited 2.

Burnout Paradise -
I spent dozens of hours playing multiplayer with my friends. I really liked the whole free-roam idea.

Not too much of a racing fan but Need for Speed Underground 2. I just love the night city and atmosphere. And of course, Daytona from the arcades, that's practically one of my childhood games.

NFS porche, loved the heck out of that game