Naw. I used to consistently get sustained readouts of instantaneous highway mpg over 100 on flat roads at 65 mph on dry days in southern California (no sub-40 F temps). My driving style was simply to hold the instantaneous mpg readout at or above 75, including compensating for rich-burn purges. I would slow down on hills to 55mph at which point I would floor it to get maximum assist. I would see regular trip (average) mileages over 75mpg, with low mpg numbers at the start from gas burned in getting up to speed.Delta Flyer said:sustained 75+ mpg is possible only driving under 60 mph.