I have a hobby car that is similar; I can get right around 40MPG on the highway and it makes more power than a stock modern version of itself. The real reason t

I have a hobby car that is similar; I can get right around 40MPG on the highway and it makes more power than a stock modern version of itself. The real reason the newer cars don't get better mileage is a few factors: Old cars do well steady state, but are far less efficient in transient states; modern engines are far better at that. Old cars have absolutely toxic emissions. I mean literal 100's of times worse than modern engines (especially diesels), which are already terrible. Couple these two major factors and you'll see where most of the advances have gone. That said, I don't think you are completely incorrect either; incentives have to be put into the right places to drive these innovations forward. If you want to see state of the art efficiency for fossil fuel engines look at trains. They are more heavily regulated for emissions than bunker fuel ships, and the amount of fuel per ton-mile used is tiny compared to a personal vehicle due to a few factors (load vs vehicle weight, efficiency of acceleration/deceleration, engines operating only at peak power/efficiency and the traction motors being electric, etc.). On a side note, the lack of parts to keep an old car in compliance with emissions is driving me insane. My hobby car is a HUGELY popular car from 20-30 years ago and the supply of parts to keep it on the road is drying up already. Due to it's factory state of tune (naturally aspirated, ~100hp/liter) aftermarket discount parts are not suitable and fail quickly, sometimes damaging other parts. OEM parts are so rare now that they are getting painfully expensive to continue procuring them, and for emissions related systems the only quality parts left are the high end aftermarket (which aren't legal). It's becoming almost impossible to keep these vehicles legal, which I'm sure is intended. I'm at the point where I'll likely run the "illegal" (though perfectly identical if used properly) parts for 23 out of the 24 months it's on the road, and only use the almost impossible to obtain OEM parts for the 1 month needed to get it sorted for emissions testing.