Have you heard of these cars from zap toys?
 

There are called the pro-racer series and in my opinion they are okay
. The speed is a little slow and there is not enough torque. After some neodyium magnets they were pretty good.
Has anyone heard of these?

zap
 

I bought a car by a brand called Zap Systems, but I'm not sure if its the one you meant.
It is not a very good car, but it is fast for the price ten bucks.