Chuckanut
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
I'm wondering how efficient an ICE engine design could be that runs at a fixed RPM, driving a generator to charge the battery. It may be, it can only be optimizes for highway speeds. I see this quote, "At 60 mph, a typical car needs 10 to 20 horsepower" So, I would think an optimized 30hp engine could driving a generator and allow an efficient use of gasoline to go long distances. A 30 horsepower ICE engine would allow a 66% conversion efficiency from gas to battery to electric motor drive. I think the conversion is higher than 66%. The obvious, is why not use the 30HP to drive the car directly, my answer would be the 30HP engine has been optimized to run a a fixed RPM and "hopefully" it's efficiency is high enough to the conversion inefficiency. There is the problem of carrying the weight of the fuel, but even 5 gallons at 40mpg will get you and extra 200 miles.
This is over my pay grade, but interested in discussion. I may be all wet on the idea that a fixed rpm ice engine could be optimized for high fuel efficiency and conversion efficiency.
I think there are weight issues that degrade the theoretical benefits. IOW, you need more heavy batteries, and bigger electric motors, etc.
Toyota can get 50 mpg from a good sized Camry. My first Camry (not a hybrid) averaged 26 mpg and I could hit 34 mpg on a long drive on a flat highway. My guess is that if a constantly running engine was more efficient in real world conditions, Toyota would have done it.