There are a ton of things you can do playing with cars. We love them at our house. Here are just a couple of things we have done with them.
Taught our oldest colors. One day while playing cars with daddy, daddy decided that he wouldn’t give up a car unless he was told the color. At first he would say the color and make our oldest repeat it. They only did red and blue that day, but it started a life long lesson of choosing colors, just by playing with his then favorite toy.
Cars the Movie, this taught us so much, but of course we watched it hundreds of times. We got to teach more colors, counting and naming the cars, more for memory as well.
Last but not least we have used them for a craft. It was on about.com and what you do is take cars that have different wheels and then you grab some finger paints and let them dip the wheels in the paint and make tracks on the paper. Its pretty cool, because later they can use it as roads to play on.
Part of being so young is experimenting and learning, let them use all their options, this is the most important time of their lives.