James Jessiman passed away on July 25, 1997. He will forever remain in the hearts of LEGO enthusiasts all over the world. For more information about James and LDraw, a program he wrote to diagram LEGO pieces (like in his images below) please see:
http://silo.riv.csu.edu.au:80/~jjessiman/
From James Jessiman on December 30, 1995:

I saw your Lego page with your entry to the building competition. You were having trouble with the wheels on the model not turning correctly. I haven't tested this but take a look at

jessiman.gif and jessiman2.gif

which may work. Connect both axles to a differential driven by a motor. Make sure they are trying to turn in the same direction. You can get the dark grey gears from the centre in set 8824 (hovercraft) although you will need one of that set for each wheel. The supercar contains enough for two wheels but is a bit expensive. Let me know whether it works and what you think of the idea.