Electric Vehicles

This question needs a clarification: what is the definition of "highway" in your country?

Here in Estonia, I can go on highway with a farm tractor, I'm just obligated to pull aside if a column forms behind me. Meanwhile, for example in Germany, going to an Autobahn with a farm tractor would quickly attract fines for a traffic violation.

I've driven on a highway with a large L2e trike (rated speed 45, actual capability 55) but did not feel comfortable there. I do feel comfortable on a highway with a Mitsubishi i-MIEV (crappy e-car, do not buy), typically driving at 80 km/h. It has a motor of 37 kW (if I remember correctly) but cruises decently enough at 9 kW of power, so a lighter car would come to highway speeds with 11 kW for sure (if well built).

I would feel comfortable on a highway with an L7e cargo quad (for which I hope to get a rated speed of 70, but that remains to be seen when it's completed), and the one I'm building has 4 x 3 = 12 kW power.

A customer of mine sells electric road maintenance vehicles, but they are type certified in the N class.

I would advise googling for "L6e", "L7e", "electric car", or maybe "electric vehicle". In my search, various Chinese products come up, but I notice that many aren't type certified in the EU, so be very careful. You want to avoid doing type approval on your own. Also, consider if you can get spare parts in the future. Find a product with local support.