If I Built a Car is a fun book written by the illustrator of the Mercy Watson Series. It's a cute rhyming story, but a little long for preschoolers. It did hold my 3 year old's attention while they were describing a car that would have a pool, a snack bar, that can go underwater, and even fly! It was fun to think about what we'd like to have in our own car.
Afterward we built our own car out of boxes. This is certainly not a new idea but we had tons of fun with it.
We used paper plates for the wheels and steering wheels and plastic cups with flameless candles for the headlights.