It never ceases to amaze me that all the people I know that claim to care about doing something about their environmental foot print just will not stop burning petroleum. Some think that burning Bio-Diesel with distillates will save our butts. Or they are just waiting for electric cars to become affordable? This is another form of insanity.
These small low-powered vehicles are the only thing that can make a difference. And then only if 90% of petrol powered vehicles are eliminated very soon. And Amerika's electrical power grid must be converted to renewable fuels. So now is the time to use less electricity as well as the dirty fuels that feed the rich.
Then there are the naysayers that claim that you must have massive power to drive two adults and 50lbs of cargo around town. That is all crap. A 40 amp hour battery pack for a 4 or 5 HP motor maybe needed and the idiot politicians won't want to let you use that much power on a vehicle classified as a bicycle. But you can sue the GD Bureaucrats if you use very low 20mph gear ratios and electronic speed limiting controllers connect to Pedal Assist Sensors [crank speed sensor]. Accelerators give you more power when needed but Cops can't very well arrest you if you can't drive your vehicle over 20mph on flat land, even if you do have two or three times the legal power limit. And if you have a large enough battery pack you don't really need more than one or two gear ratios.
Custom Motorcycle vehicles take more than just larger tires and a larger frame; they have to be able to drive at least 45mph without falling apart. And they would need to be tested by the motor-vehicle department. Building a power-assisted pedal-powered vehicle can be licensed before you put a motor on it.