Scientists in the U.K. worked with a music producer and created a bunch of music that simulates the driving sounds that put kids to sleep. It doesn't sound much like a car though. The driving sounds are subtle, and mixed in with"white, pink, and brown noise...
Oh sleep, how much we love it and need it. There are such things however as sleeping too little or too much and a couple sleep conditions you need to be aware of so you're fully energized every morning.