As mentioned, there is a class of vehicles called a "Neighborhood Electric Vehicle (NEV)". Small, slow moving, etc. Pretty much glorified golf carts. I'm not sure about licensing, but they are pretty widespread, but may be limited from running on streets with higher speed limits. I.E. I can't drive one home if I must drive on 55MPH streets/roads.
3-wheel often bumps a vehicle under motorcycle rules, but that may also require helmets and motorcycle licenses to operate.
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I think a growing class will be the E-Bikes, which can include velomobiles (electric?), and often 3-wheeled. Currently little regulation, and many people hope it will stay that way.
https://en.wikipedia.org/wiki/Velomobile
A low center of gravity likely helps the velomobiles, but I have to wonder of a narrow wheelbase is a problem on the trikes.
Also the E-Cargo bikes.
