A vehicle could be some more efficient without added bulls***. Older Cummins will get better mileage then a new one and can easily match on power. Has NO electronics on engine.But it’s an exception somewhat.
I agree added tech can help and we’ve seen that the largest with addiction to FI on gas engines. If an auto manufacture spent as much time on efficiency as they do the next best option that everyone HAS to have things would be different. I do believe there is money passed under the table to curb great mileage, and I truly think if people don’t see that they are blind or don’t care. There are still mechanical things that can be done, weight savings, aerodynamic improvements, and fuel controls that could be looked into. The new Ram uses generative alternator that doubles as a super charger, that’s a step. There are many more out there if it mattered. But it doesn’t! People don’t give a s*** on average if thier rig gets poor mileage they’ll still go to the pump. People aren’t screaming for better mileage so the manufacturers are doing what sells and not getting much better.