One conversion I want to attempt, but am unfortunately unlikely to, is an electric rear wheel drive.

Front wheel can remain gas with transmission. Add more generating current capacity, and have that dumped into the rear drive system batteries.

With my current car, the V6 gets very good economy at speed, and poor economy in town or in traffic.

An assist from the rear can tackle the poor economy cases nicely, leaving the rest to the gas engine.

Depending on battery capacity, I suppose it could do most in town driving at say 40 and below.