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Old 11-12-2010, 02:15 AM   #25 (permalink)
Dr. Jerryrigger
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Join Date: Jun 2010
Location: mass
Posts: 181

The Sh*t-Box - '99 Subaru Impreza Outback Sport
90 day: 27.81 mpg (US)
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Quote:
Originally Posted by RobertSmalls View Post
Not true. In theory (and in practice) rolling resistance is proportional to vehicle weight. The question is whether the improvement in engine efficiency from easier P&G outweighs the increased rolling resistance. For most, the answer is no.
oh yeah, forgot that one. The tire patch will be proportionally larger on the higher mass car. And there is also mechanical rolling resistance, and this is one that could go either way. It is far more likely to favor the low mass car (less weight on the bearings) but depending on the suspension more mass could make the universal connector have to bend less and reduce resistance there (or make it worse).
There are really too many variables to accurately predict any outcome of this, but as always the key variable is the driver. It take time to get good at P&G with a new car, and that's basically what the high mass mod is. On this point, if you can get the same mpg right from the start, would a few months of practice give you better mileage? there is really only one way to find out.
If we look at it in the real world I think the differences between the high mass and low mass car will be minute, with the exception of getting up to speed. A little city driving could really kill a tank's number.
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