How cute! You can probably find hot wheels fabric at Jo Ann's or Hancock fabrics (our walmart doesn't carry fabric, maybe yours does), so I'd start there to get a color theme or something.
Then you think about the walls- solid or maybe a hot wheels border. You could look for a rug with tracks on it to drive cars along (or paint one on the floor if it's hardwood). Look for some ways for him to display his cars and get to them to use them when he wants- shelves or a little hanging case that can be shown off.
My son's room is firefighters/ dalmations and his fan is painted red w/ dalmation fan pull, &walls are blue, with one (with the door, so you don't see if unless you come in and turn around, because his room is soo tiny I didnt' want it to look cluttered) that has a dalmations border and I painted bricks underneath. I hung a ladder on the wall. Found inspiration searching "bedroom themes"
at 10:56 PM on May. 26, 2010