Quote:
Originally Posted by changzuki
it's all about energy used whether expressed in watts, hp, whatever.
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You are thinking racing, not fuel economy. Generally in real world driving, lighter can be better because you do have to use the brakes occasionally and no one is going to religiously PnG. But with PnG adding mass to a grotesquely over powered vehicle such as most motorcycles will improve FE. Your comparison with human power is forgetting one thing. The brake specific fuel consumption of a combustion engine is terribly inefficient over all but a small spot on the map. The difference between the optimum operating range at 35% efficiency and the average of 15% is huge. Soaking up the energy that is delivered at the optimum range is difficult. Even the meakly powered CBR250R will absolutely average better FE on a real world cross country trip with 250 pounds on the bike instead of 150 if Pulse and Glide is used. Stressing out over reducing total mass in a hypermiler is a big misconception. Performance suffers with added weight, but FE not so much if you don't touch the brakes.
Back to the bikes. A human powered vehicle weighs 5 times more than a road bike but goes 3 times as fast due to the better aerodynamics.
Sorry, rant over. Replacing the lead battery in your pick up truck with lithium in order to improve the fuel economy is a huge waste of money.