Hey, how about we tax cars by energy efficiency?

Just take the energy you put into the vehicle, check much you need per distance (you can re-use the EU standardized course to determine fuel consumption) and multiply with x €/cent?

This would intentionally ignore losses getting that energy to your car, be that Oil refineries or Power Plants.

What would we get?

I’m lazy so i asked some llm to do the calculations ..

That seems to check out.