When my s-i-l told me she was going to decorate her new nursery in the Cars theme, I had the perfect gift idea- a custom Cars name mural:
I painted this one on a canvas drop cloth- I have also used canvas on the roll bought at fabric stores. I have started painting a lot of my children's murals on canvas so that they can be easily removed as the child grows. I install them with wall paper paste when finished. *Note: you need to paint the back of the canvas as well so that the canvas doesn't adhere to the wall permanently!
I also created a matching one for his older brother who shares the room, plus a cheerleading one for his big sis: