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.
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?