Something I learned when I worked repairing pinball machines and video game machines-
There are some mechanisms that only work well when dry.

Just as was said before, petroleum jelly will:

a) Attack the plastics in the chassis, making it soft, and ruining it.

b) Attract and hold dust and debris, thickening and making an unpleasant performance-killing paste.

I personally use nothing. Even a dry lubricant can potenially collect in lightly oiled places within the motor itself.
If someone could prove it makes the plastic wear slower I might consider it though.

I clean the gunk out with a brush from a pile I have from old electric razors, and maybe use a can of air with the tube on it to blow out the dust. That's really all you should need.
I also ditched running my cars on carpeting, since it is ALL fibers.

I like that everyone is always thinking of little things to boost the performance of these little cars, it's great!
There are some great ideas being circulated.