Finally, one day, as we were playing in my son's room, and he had dismantled most of his toy cars, I said, "It sure seems like you enjoy taking apart your toys."
His response "I do, mommy, I really do!"
"What is it that you like about taking apart your toys?"
"Learning to fix them and build them!"
I thought, "oh what I wouldn't do for an old fashioned erector set!" My family happened to be at IKEA the next day where we picked up a BYGGA - the Swedish version I guess of an erector set. We took it home and learned how to build a motorcycle from the set.
My son is learning to build things, and I am learning to assume that children have the best intentions at learning (not destructing).