Regulation is exactly the reason why there are few technology improvements. Improving the engines is pretty trivial. Heck, Diamond adapted car engines for their

Regulation is exactly the reason why there are few technology improvements. Improving the engines is pretty trivial. Heck, Diamond adapted car engines for their aircraft. _Certifying_ them is hilariously expensive for the manufacturers and users. One can certainly fix that, but that's how it is. Main reason why the planes that consume automotive gas the most are in the 'experimental' category.