When I was seven years old my parents got me a Green Machine. Let the record show that at the same age my son was doing 40+ mph in a TopKart --- but that's the difference between having hip urban parents like I had and a hick-ass of a dad like my son has. Despite its lack of an engine or anything approaching high-speed stability, the Green Machine was actually a lot of fun and I rode it until the plastic front wheel showed genuine signs of deterioration.