They design, I cut it, they paint and put it together. I advise, but it's their
car. We have a good time. And they've lost every friggin race they've ever been in. Even the car I personally built for my 6 year old - that car sucks too. Actually, my oldest started winning races when he put his car on the track backwards, but it was too late in the derby to make a comeback.
Used to think the race was fun, but there are too many dads that make their kids' cars. Because of my pride, I can now judge those dads and know that I am so much better because I allow my kids to fail miserably.