5-10 years ago (that would be 2007-2012
) someone showed up at a local show-n-shine with an electric Rabbit that had been converted as an experiment by the Sate of Oregon (lead-acid & etc.). It had a gas pusher trailer that had been made by cutting down a cabriolet. That made for a nice little trunk on the back
I now have a 1979 VW non-turbo diesel as well, so the subject of improving the efficiency is of interest. Have you seen this picture?
Right now I'm over-restoring a roof rack. Then I shall lift the rear instead of lowering the front and add front and sides air dams. Followed by a difusser with fences.
My overall strategy for more efficiency is to swap out to a Buick Lacrosse altermotor for the stop-start and KERS.