In sub 50F weather, winter blend gas, 87 octane and not premium... i see roughly 33-36 mpg at 70mph in charge sustain mode.
Not great at all.
On the other hand, on the 1 or two days it has been 60F+ outside with light winds, driven at 60mph, again with regular 87 octane winter blend I have seen 45mpg over about 30 miles of straight highway. The car will "pulse and glide" with the generator. It drops to its lowest output and if it still overcharges the battery, it will shut down and run on battery until the pack drops below a specified threshold.
Gas only mpg will most likely be lower than a prius in every driving scenario, but the fact at it also has roughly 9.5 kwh of EV range means it is on par with the prius in most situations.
__________________
|