I suspect the driving with load technique works best with lean burn engines, Atkinson engines, or diesel engines, all of which can run efficiently at low throttle settings. Since the standard ICE (with no lean burn) in my car runs less efficiently at low throttle settings, I find I get my best mileage on rolling terrain with downhills gentle enough that I don't have to do any braking (either friction or compression) to keep the speed from becoming excessive. Since my standard ICE runs most efficiently at about 70% throttle and below 2000 RPM, I can climb the hills at whatever speed this throttle setting gives me and then coast the downhills in neutral (and sometimes even with the ICE shut down). With my engine, this uses less gas than traveling the same distance on a flat road at a lower throttle setting.