The fan in cars is typically not enough to keep it cool while stationary under load, but in typical home applications you won't have that big load anyway. Big load for a car is >10kW. You can also pretty cheaply get a bigger external fan, like those used on dynamometers.
One nice side effect of using car as generator - free heat in winter if you extend cooling loop to your home.
One nice side effect of using car as generator - free heat in winter if you extend cooling loop to your home.