You're drownshifting uphill not to save gas, but to get back into the meat of the engine's torque curve, or to its lower end so you can maintain or build as you accelerate. Likewise, downshifting downhill wastes gas but saves brakes. Tradeoffs. Fuel efficiency always favors the tallest-geared lowest-revving pairing that has sufficient torque for the given task, counter to "responsiveness." Performance:efficiancy, an inverse love story.jscully wrote:I dont think I have it wrong on the revs. If youre geared too high it bogs your engine down and you use more gas. That is why auto trannys downshift. You may experience this going up I-70 or anything like it. If youre geared lower your engine revs will be higher for the given gear and thus less downshifting saving you gas.
So tying back to the OP's Q, it may be worth comparing the breadth of torque curves and the width of gearing with a low Lo for the rough. high top gear for highway, and a healthy curve overlapping the gears in between. Upsizing tires shifts that, and factory settings can be biased either way.