My opinion is you could try letting the kids build a car more or less the way they want, and not worry about applying all the ‘tricks’ in the book to ‘win’. Ask the 10 year old where *he* thinks you should put the weights. Let him design the shape and apply a cool kid paint job.
Or you could buy a 3-axis cnc machine to mill out the body, polish the axles with diamond dust and coat them with the finest graphite you can find so your kid can learn all about ‘winning’.
