Honda EU2000i inverter generator
It's also pretty inefficient with the fuel.
It is very efficient. Unlike a normal generator it can adjust the rotation speed depending on the load. This saves lots of fuel at lower loads.
All the Honda units run the engine slower at light loads. But the bigger ones make more electricity from less fuel.
It does make me wonder how they react to sudden increases in load. There may be a really serious voltage droop while they accelerate the engine, unlike something that is already at speed. Unless there's energy storage (battery, capacitor, independent flywheel) sufficient to cover the deficit for 1/4 (?) of a second.
The 2200 W unit uses 1.14 l/hour at rated load or 0.52 litres of fuel per kWh
The 7000 W unit uses 2.9 l/hour at rated load or 0.41 litres per kWh
The bigger unit is 27% more efficient.
More than that, if you run the 7000 W unit at 1/4 power (1750 W) it will run for 18 hours instead of 6.5, for about 1.05 l/hour or about 0.6 litres per kWh, so you're not losing much at lighter loads (unless your lighter load is 500 W or something)
It's all pretty expensive electricity. At my current local prices for regular petrol the 7 kW unit is US$0.69/kWh. The 2200 W unit is $0.86/kWh.
That's not counting depreciation and maintenance.