I would think if a series hybrid were more efficient than a conventional mechanical drive and transmission, it would already have been adopted. Trucking compani

I would think if a series hybrid were more efficient than a conventional mechanical drive and transmission, it would already have been adopted. Trucking companies will spend money even for small gains in fuel efficiency because they drive so many miles. I also think that regen braking in semis would be trickier because a lot of the braking happens on the trailer wheels so you would need to fit all the trailers with regenerative braking equipment.