10 posts, and 1 minor remark about the 2 different threads.
In short, there are 2 things you need to consider.
Frame rate on display
This is basically what you see. Everything far over 30 FPS is not visible by our eye sight. We capture around 30 FPS with our sight.
Second, and this one is more important in relation to all different kinds of lag. there is the FPS for the physics. Indeed, as said above, this is a separate thread.
In short, you can have 100+ FPS on screen (kickass video card), but a to low physics calculation rate (normally around 400 - 500 FPS), which causes stutters and lag. It's a combination of the both that gets you smooth gameplay.
Theoretically, with 30FPS on screen (in lowest moments, so during start for instance), you should have no problems driving, IF the physics FPS is high enough.