I've sometimes wondered if it would be viable to build a "range extender" for electric cars which is basically a generator which is designed to integrate with the vehicle, but can be easily removed. Then people could fit them when they were going on longer trips converting the car to a plug-in serial hybrid. Car dealerships could perhaps rent them out and do the install/removal.
Range extenders exist. The 2014 BMW i3 offered one as an option. But now that batteries can provide 200+ miles of range there's less need for them and most EV companies have stopped making them. (Of course this hasn't stopped people from building their own.)
Even for high range cars, this makes so much sense to me. The biggest situation keeping me from getting an electric truck right now is towing something long distance since it kills your range, and often the long distance is way out in the middle of nowhere away from any chargers.
This might be oversimplified, but trains have been giant diesel generators powering electric motors for decades now, so why not add diesel generators to cars?
It does make sense if you need a car with extra-long range. Locomotives are diesel/electric hybrids not specifically because of range but because they need the torque that only electric motors can provide. If it was only about range, trains would just run directly on diesel engines.
Until recently batteries with the energy density needed for trains didn't exist, so the diesel generator was a necessary part of the equation. That is changing however, and battery/electric trains are now being tested.
