Why don't electric cars have a small built in gas powered generator?

I am not talking about a hybrid car with a combustion engine, but it seems like a small, cooler sized gas generator could be added to a car for emergency charging. Sure, you could carry one with you, but it would be more convenient if it were built-in. Plus, I do not want to have gas inside the vehicle’s cabin.

Hey Ashley, that move could be tricky. Charging at 110 volts from a gas generator typically provides an average of 4 to 5 miles of range per hour of charging. Customers are unlikely to wait by the roadside for an hour while a generator runs just to gain 5 miles of driving range.

Some cars do this, this is the way the first Chevy Volt worked, the gas engine mostly charged the battery, although it could be used a bit to augment the power at highway speeds, but not on its own.

Because battery production has increased to the point where it is cost-effective to install the needed battery capacity, the serial hybrid component is no longer required.