Quote:
Originally Posted by oldtamiyaphile
The answer is simple they assume a gas/brake driver. For a hypermiler extra weight is just stored momentum, it's like a hybrid but with 100% efficient energy conversion.
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It is a good point. But it applies less in typical conditions than we might assume. If we are in perfect hypermiling conditions on a track and can completely coast down to stop without traffic interruptions, then the gain and loss would I guess be equal like you suggest. But most driving is not even close to track conditions--especially non-freeway driving. We have to use brakes sometimes. We also have to start from a stop on a hill sometimes. Additionally, some rotational mass savings are MORE effective for hypermilers who use the P&G technique. For example, a lighter flywheel or lighter accessory pulleys waste all their momentum when a driver cuts the engine at speed and shifts into neutral to glide. On the next pulse, that mass has to be spun up again--only to be entirely wasted on the next glide a few seconds later.