It's not a puwede na thing, but realistically, developing an engine with stuff like high pressure direct injection is aiming for a crowded market with high barriers of entry.

You aim for the developing markets. Develop a small engine that's fuel efficient and sufficiently cheap to maintain. Develop a small car platform that's robust... Or better yet, a utility vehcile platform that's more efficient than current. This isn't aiming low. This is aiming for where the profits are in mass manufacturing.

Sadly, it seems the only segment you can enter where being small is not a disadvantage is making ultra-luxury cars... But it's not a great market, either.

Personally, easiest out... Offer to manufacture the T25 for Gordon Murray. That's already been engineered. It works, it meets all standards. Develop a five-seater variant. And work at reducing tag price to the 400-500k level for the three seater.