I have a couple of Honda sine wave inverter-type generators (eu2200i and eu3000i) for running test equipment and for backup power during very infrequent power outages. I made neutral-to-ground bonding plugs (one with resistor and one with solid copper bond) to use when necessary to have neutral referenced to ground. I use the car as a load bank to run the generators under load once in a while. As someone already mentioned, fuel efficiency is only about 25 miles per gallon when charging with the eu2200i. Efficiency is similar with the eu3000i if I use a 3 kVA step-up transformer to charge at 240 volts and 12 amperes (generator output of 24 amperes at 120 volts). Voltage regulators and engine speed governors of some inexpensive generators may not respond quickly enough to handle the quick current increase when the car starts charging, but the Hondas work well.