Alpine wrote:TallGrass wrote:You could explore "hypermiling" with your Tacoma such as .... seeing if they make a taller rear end (gear ratio),
Primarily, the idea that engines (actually not only the engine but the entire drivetrain and even the overall vehicle itself) are tuned as a system - generally to make best use of the engines torque curve. So that if you changed the gearing to a numerically lower number it is possible that the engine is actually becoming less efficient and instead using more gasoline rather than less?
Maybe the idea of a re-gearing would work, but only as long as if it didn't push the engine too far outside its torque band.
Rear axle ratios are a trade-off - shorter ratios, that is higher numbers, are faster off the line, tow more, have more engine RPMs and wear, and have less (stick shift) clutch wear on take-off. Taller ratios, lower numbers, reduce engine wear, are slower off the line, tow less, have more clutch wear on take-off, and almost always get better mileage. I've seen a linear ratio from a rear axle change - 20 percent higher ratio (lower number) equal 20 percent better fuel economy.
Surprisingly most manufacturers are still gearing stick shifts for off the line performance rather than optimal gas mileage. They still seem to think all stick shift people are hot-rodders looking for off the line performance. That's likely to change as it gets harder to meet the fuel economy standards. The other thing they've screwed up is that six is too many gears for optimal fuel economy. If you want improve stick shift fuel economy, skip gears. Fewer wider spaced gears is more fuel efficient with a stick, the opposite of an automatic.