Quote:
Originally Posted by stillsearching
A related question if anyone has a comment - i'm wondering whether top gear is always the best possible efficiency for a vehicle at lower speeds, could going even slower in 4th achieve better mileage?
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It is possible on some vehicles that the 2nd highest gear at a lower speed (than top gear's lowest non-lugging speed) will be more efficient.
It will depend on gearing & aerodynamics of the particular vehicle.
EG:
from Honda Ridgeline MPG vs speed graph: fuel economy with & without cargo trailer ...
The leftmost 3 points on the graph are in the 2nd highest gear. Probably a function of the truck's relatively high aerodynamic drag (and the fact that it's an automatic transmission with a programmed speed-based shift point) that makes cruising in 4th at a lower speed slightly more efficient overall than top gear.
See more speed vs. fuel economy graphs:
http://ecomodder.com/forum/showthrea...you-15182.html