My Son works for a bicycle mfg and recently he obtained a carbon fiber frame from work and custom made a bike with a little 1 cylinder motor on it and started riding it to work. About 4 miles 1 way. It took him a month to use a gallon of gas. I rode it and it is fun. It will go 30-35 top end but it cruises nice at around 20mph or so. We clocked the speed of it with a car. Now everybody in the shop wants one.