They set the karts to different speeds based on the height of the riders. They determine the speed of all the karts by the height of the shortest person in that race. The highest speed is comparable to a traditional gas-powered go kart.
They are awesome! Twice during your run you can turbo x 10 seconds, but do it on the straight aways or you cannot make the turn.
The go karts can get up to about 15 mpg. I got one that would break automatically few seconds.
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