First did you know US MPG declined 0.1 MPG 2020 to 2021. Of course consumer desire for large SUV or trucks plus add 4 wheel drive. Second did you most plug in hybrids are not plugged in. I have friends averaging 1000 MPG but they plug in every day. Central to lowering fossil fuel for light vehicles is produce something folks want more then alternatives and will in fact use.

Next point, you are using maintenance cost for total market. EV is rapidly evolving. Tesla are winning lowest cost of ownership in police, Uber … my assumption is all vendors will match best of class or they will go out of business.

In the US the shift to wind solar and battery/hydro etc is clear. The cost to produce is lower then coal and gas.

Oil is basically unstable as Middle East Russia … use it to win their local self interest. Shifting to clean energy grid is a massive investment but strategically equal to defense spending.

Not discussed much are the cost in pain early death and medical cost of local pollution from oil processing and use. Plug in hybrids do little to mitigate this issue. 25 million in US have Asthma, many of the attacks are linked to gas car emissions. Pollution from oil processing is a localized risk for cancer and lung disease. Water pollution and ph shift affect food production and drinking water. Cutting this in half would be a big win.

Could you make plug in hybrids that drive gas use down by 50% is not the question. Can you make this type of vehicle that consumers will want? Tesla is already winning the consumer vote.

As a EE I am biased. My bet is the EV eco system will drive performance to price improvement on the order of 2x every 5 years. Just my guess based on my experience with the electronics industry. Gas evolution can improve but unlikely given the trend in consumer preferences.