Okay, i've worked with a racing car game (side-project) and i wasn't sure, how you increase the max speed, but the acceleration is smaller.
Sometimes it just screwed up, the brakes didn't work while changing acceleration, and sometimes it accelerate so fast, that the skid's made a broken line, and it was strange when i burned, then the skid's made a tractor's wheel shape. Well, so that's not bad actually...
I suggest you add these to it
-Available to buy some new mechanism, like motor or brakes, it would be very cool cause i am not sure how to modify those scripts.
(Actually i tried but i screwed, like i said earlier. )
Otherwise, still i think this is the one coolest example here
Seems like you are using the old scripts, try downloading the most recent ones.
About those suggestions. I think these features goes outside the borders of this example as this is not a racing game example.