What's great about putting the electricity in the batteries is the batteries can store that energy for quite some time. And when you do use the electricity the motors are very efficient about using it.
Gasoline ICE engines produce 20%(varies) mechanical energy and 80% heat energy from friction or escapes as heat. It uses all of the gasoline you put in it(except for the stuff that evaporates) but only 20% of the energy is in the form of mechanical energy. The driveline on a manual transmission vehicle is approx 85% efficient which is on par with electric motors after you run the electricity from the batteries through the controller to the motor. So best case, an average of 17% of the energy from the gasoline is used for movement and 72%(varies but 85%x85% is average) of the electricity from the battery becomes movement. If you run a generator you're going to lose energy from the charging process. In the end an electric vehicle uses about 1/3 the energy of an equivalent gasoline car would get with similar power outputs and energy usage. Most generators are 2 cycle for the power and light weight. They get half to one-third the fuel economy of 4 cycle engines.
27.5kw might get you 100 miles at less than 45mph. Why are you calculating 80 watts-hours/mile? Even if the EV1 consumes 80 watt-hours/mile after you convert the energy from the generator to the motor it's going to use more power than that and you aren't even driving an EV1.
You can't just convert miles + energy = time. You're ignoring speed. 27.5kw-hours will only get you a little over an hour of drive time at 60mph. 27.5kw-hours doesn't equal 340 miles of driving at 100mph for 3.4 hours. Not even in an EV1.
Hooking up a generator to your Electric vehicle is as easy as plugging in the charger. 2.5kw chargers are expensive too,
Zivan makes one but they sell for over $1k.
Going the EV route with a home generator would just consume more than your current car does. Except for the short range all electric trips. It really depends on your personal commute, which for you Nerys does not sound like an economical choice.