Mazda RX7 and RX8 had wankel engines. Nice cars, but higher maintenance than with normal engines. I think the main reason for the pattern you observe is that w

Mazda RX7 and RX8 had wankel engines. Nice cars, but higher maintenance than with normal engines. I think the main reason for the pattern you observe is that what's optimal and what's cost effective in a car is highly non-intuitive. Take front-wheel drive, for instance. Mechanically more complex than RWD, but (apparently) worth it due to the space savings inside the car. Or take water-methanol injection: well-understood tech that's been in use since WW2, can save fuel and reduce NOx emissions significantly, or give higher power output. But it requires changes to all the fuelling infrastructure, and that makes it essentially a non-starter outside of racing cars.