Here's a nice page explaining the system -- a serial hybrid. https://www.nissan-global.com/EN/INNOVATION/TECHNOLOGY/ARCHI...

According to the page, you can't plug in these vehicles, is that right?

Chevy Volt was conceptualized as a serial hybrid iirc, but the engine drives the powertrain at higher speeds so it's not a pure serial hybrid. Mazda has a rotary engine based serial hybrid / range extender out or coming out too I believe.

They have cost challenges - because if you want to drive one at a constant 80 mph on the freeway, you need at least ~50 horsepower of gasoline generator, ~50 horsepower of generator ~ 50 horsepower of generator inverter, ~50 horsepower of motor, ~50 horsepower of motor inverter.

Turns out all of that costs and weighs a lot more than just 100 horsepower of gasoline engine for a similar size car.

Cars like the BMW i3 with range extender undersize their gas engine and generator to save money and weight, yet are getting sued because in worst case conditions (driving up a mountain heavily laden), sometimes the car runs out of battery power and has to rely on gasoline alone, leading to a top speed of only 20 mph - not really usable!

I also don’t see why 50 hp is a good target. The oldest Model S cars can drive on the freeway (at moderate speed) using maybe 25 kW (33 hp). So a 25 kW generator would allow indefinite freeway driving at moderate speed. But almost no one does this except maybe long haul trucks that trade drivers.

IMO the right way to think of it is: a 25 kW generator will almost fully recharge the battery in under 4 hours. If you drive uphill or fast for two hours, and you run that generator, you have an extra 50 kWh. If you want to drive 10 hours (shudder), that’s an extra 250kWh — you should avoided about three long charging stops, so maybe one actual level 3 stop gets you there even if you drive moderately fast.

And you can stop for the night (or sightseeing or whatever, as long as you park outdoors), and you’ll be fully recharged afterwards. I would appreciate a 5kW onboard generator for this purpose!

Nobody is putting much R&D into new engine designs.

Lots of countries have laws saying an engine in a car can't be running without a driver present.

For all those reasons, tiny range extenders on large batteries don't tend to exist.

Instead you get moderate or large range extenders paired with smallish batteries (ie. total range 50 miles). And they still have trouble if you drive fast, heavily laden, up a hill, on a hot day for more than the battery capacity.

To add: you can always run the engine at its most efficient rpm, getting the most out of every liter of fuel.

I’m 100% certain the market could exist. Probably the difficult part is car manufacturers supporting it and possibly some engineering problems (low probability of problems I think).

There are lots of pluses to not having a transmission, and always running your engine in a narrow, tuned, power band