a friend and I have talked about doing something very simaler, in wisconsin a bicycle is defined as having pedals, and atleast 2 wheels that are no less then 16" diamiter, if operating at night is must have a front and rear light visiable from I think 500 feet... that's about it, no limit on number of wheels, no limit on weight or size, it just has to have pedals.
A motorized bicycle is a bicycle that the power source that can be removed without affecting it's use as a bicycle, and not alowed to travle over 30mph while powered by motor or engine.
it's not untill you get in to the relm of motorcycles and mopeds that they put wheel limits of 3 wheels, or a weight limit of I think eitehr 1,200 or 1,500 pounds.
That car defently is a bicycle, and if he was going to get a ticket I would think the only reason would be if his city required it to be regestared as a bicycle...
