Wankel engines can't compete with piston engines. They are essentially a '3 stroke' engine, and get poor fuel economy, and produce a higher level of pollution, requiring extra pollution control equipment, which, you guessed it, decreases fuel economy.
If Wankel engines actually worked well for passenger vehicles, they would be in EVERY car being manufactured today. Why aren't they?
Yet, despite the early claims, they never became the engine that was going to replace piston engines, well, everywhere.
I had a co-worker that bought a small (about the same size as a Toyota Corolla, at the time) used Mazda with a Wankel engine, in the mid to late 1970's. I can't remember the model name or number, but IIRC, it had 3 rotors. She got 11 miles to the gallon in city driving, and 14 MPG for freeway driving. She spent hundreds of dollars at the Mazda dealership, trying to get it to run properly, or at least get decent fuel mileage.
She wound up trading the car on another used car, a Honda Civic, which got TRIPLE the gas mileage in city driving, and almost triple for freeway driving.
This is why only Mazda was foolish enough to put a Wankel engine in their cars. They were a pretty dismal failure.
And the RX-8. That resurrection of the RX-7 was such a resounding success, it lasted a whopping 8 years of production.