It's not just HSD. Tesla uses a single speed fixed reduction, 7.[something]:1. Wolftronics has a planetary reduction gearbox that will bolt to Siemens and UQM motors and pass 500hp at 2:1.
My Lexus rear drive has technological magic in the buried permanent magnets that reduces back EMF.
A vote for re-jiggering a classic, the Golf GTI W12 650:
I like the bodywork, but don't require the 202mph top speed. You could even use the Prius four in back instead of the V-6, with an MGR replacing the gas/diesel front engine, and unbalance the gas/electric ratio.