In answer to McGrath's original question I do know of a solution although it can be distressing for all concerned. I will, however describe it here but please don't shoot me.....

Put on thick leather gauntlets.
Hold kitten firmly under engine of car - a harness would be good aswell.
Have someone switch on engine.
Hold kitten under working engine for several seconds.
Take kitten back into house and give it treats.
They tend to avoid cars afterwards and are very careful with roads.

Might help!