Great. So now it's revealed you're bashing it without even a basic understanding of how or why it works.
Alright, giggles aside, think of it this way:
First, you have to realize that
the two are asynchronous. The physics engine isn't working on the same six numbers in the background for every frame.
The simulation is actually running at 360hz -- the car is moving inside of the console, at 360hz, and we're only updating the graphics when we need to, at the limit of the television -- 60hz.
Why is that important?
Well, consider a bumpy track, such as Le Sarthe or Sebring:
http://www.youtube.com/watch?v=73MvmT5C-ik
Now, remember that computation physics is all about sampling. It's not continuous, we're really just measuring what's going on with the car "every so often" (where "every so often" actually means hundreds of times a second) and applying the forces to it, to get ready for the next measurement.
135 miles per hour is about the mark where you're doing 60 metres per second. Meaning that a 60hz (60 times a second) physics simulation will only be measuring the road at a resolution of 1 metre.
So what happens if you have a bump that's one foot across?
Let's say it's a speed bump. About a foot in length. See what's going on here? At 60hz, your simulation might skip right over it. The game will see smooth road on the first frame, move one metre ahead, and see smooth road on the next frame. It's completely missed the bump that was there
in between the two measurements.
That's why they run at 360hz. In effect, it's a problem of resolution. 360hz means you can scan the ground for track variations at a much higher resolution -- at the aforementioned 135 miles per hour, that means every 10 inches, rather than a full meter. That means you can catch all the subtle small bumps and groove of a complicated surface like Sebring or La Sarthe.
It doesn't matter as much on a completely smooth track, such as Suzuka. But on other tracks, it can be like night and day.
And that, in a nutshell, is why a high simulation rate is important.