[aerohead]

AeroStealth put this to the test.
His 2014 Ford F-150 EcoBoost, crew cab, 4X4, with 6.5-foot bed:
22-mpg at a constant 62-mph.
32-mpg at a constant 35-mph.
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The big issue is traffic light synchronization. There isn't any! The transient loads of stop-and-go driving rip an ICE vehicle a new one.
10-speed transmissions are two gears away from CVT economy, but there's only so much one can do.
That's why we have hybrids. BEVs are on the right side of the calculus as well.
ICE won't regen.