An easy way to tell if your kid will be into cars:

Place your kids in a wagon at the top of the hill. Observe.

1.)If the kid gets out of the wagon or does anything to indicate they ain't going down, they are probably not going to be into cars.

2.)If the kid goes down in the wagon, but starts screaming/crying halfway down and either sits in the wagon or runs back to you crying, they are probably not going to be into cars.

3.)If the kid goes down the hill, immediately starts to squeel and laugh, pulls the wagon back up the hill to do it again and WILL NOT leave until you pick them up and carry them... you got a kid that's going to be into cars.

I was firmly in category 3.

(This test also works with sleds, slip and slides, bikes, etc)