i don't think i fully understand
at my college, there was a big hill. every year the engineers competed in a soapbox derby, with some really pretty incredible builds. To prevent windup motors or gas/electic actual motors, the rule was "the car must be entirely gravity powered"
well, some clever fellas figured out they could hoist up a buncha bricks, and use them descending to drive the wheels. it's stil technically gravity powered but gives them an unbeatable leg up in acceleration vs the competitors.
in the end, it wound up working too well, they got going too fast and lost control toward the end, spun out and DQ'd. similar approaches were banned in future runs. still, i always liked that one - very clever.
winner was a team. "team abraham lincoln" which included julian who used to be on here, part of the guns, built "the internette" moby/derbi/hobbit hybrid. just a real laid back trike on bicycle wheels. it was fast, and also played the ping island strike theme from life aquatic, pretty great. mine was a very mariokart looking framed bike, themed after gremlins (the amc car and the furry menace movie) and equipped with multiple squirt gun turrets for crowd suppression. personaly favorite was a toilet car, driver sat on the can and as it ran down the hill it flushed out the toilet leaving a nice funny river of fun. much lols