Now that you’ve seen this, and know it exists, and can see how to build it, you are now obligated to build one for your child – if not, you’re a bad dad. Go, build it. You are only exempt if your child is old enough to legally drive.
Just kidding! I find it cool that the builder, an adult, built it for himself to race in an adult soapbox car race! Bigger pic, video of the R2 in action, and a link to the “Instructables” page are all after the break.