Uhh! What an interesting thread! Thanks for the necro, I'd say!
I had some thought-experiments, one specifically about the engine: a V6, with a 90° bank angle and a flatplane crankshaft! Could take the PRV V6 as a base, so one would then 'only' need to make or rephase the crankshaft and cams, new firing order etc. . It would be interesting in the way that it would be balanced like a 90° V-twin, on top of possibly sounding like this Laverda inline 3 which also has a flatplane crankshaft!
But, what car would I put that in? Split about that, actually, but options and reasons are:
Peugeot 309 - Some nostalgic value, as my mother drove one, and it was such a charming little car. The V6 would make it a pocket rocket, though!
Peugeot 405 - Also nostalgic value, my father drove one. Give it the V6 it deserves!
Citroen BX - Hydropneumatic suspension, and the appearance of a retro-futuristic electric car.
Chrysler/Talbot Sunbeam - An intriguing hatchback that doesn't quite look like much, but it has RWD! You know what that would mean with more power?
Insanely fast tofu deliveries!
Actually... let's just take the Citroen BX and equip the 4x4 version with quad electric motors, one for each wheel! Then drive it through the night, looking at its new-age digital dashboard while listening to some Perturbator, the hydropneumatic suspension making you glide through space and time!
I really find the smooth and quiet electric drive would do that car good justice. Though, the letters on the RPM counter would kinda lose their validity if that display would be used as a power meter instead.