Quote:
Originally Posted by California98Civic
On this site we have occasionally had the "does weight reduction help fuel economy discussion." A rule of thumb is that the savings come only when you have banked up lots of weight reduction. But there is no way for people with our materials and conditions to test claims.
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Actually with the help of a trailer and coast down test you can:
Quote:
Originally Posted by oldtamiyaphile
Don't bother.
My van averages 6.7 city (16mph average speed) and on a really bad day 9.7 with a 500kg+ trailer.
If you work that out that's 0.006l/100km per kg.
Those are worst case figures because a trailer also adds rolling resistance, rolling inertia and completely ruins my aero (it's a big tall box). I also EOC normally but rarely do with the trailer.
My van had a 0.33 CD and I coast down tested the van+ trailer at 0.45CD
If I type those numbers into the calculator, I find that with a .33CD I should be getting ~6l/100km at 50km/h, and with a .45CD I should be getting 8.7l/100km. So it seems that my 500kg trailer is only costing me an aero penalty, the weight is doing little to nothing.
A lighter car will sit higher on it's suspension so could actually cost you economy at higher speeds.
So on my new van I happily fitted a heavier radio, speakers, sound proofing and even an active sub, as the comfort, convenience and enjoyment is worth the extra 0.000-0.001l/100km or so it might cost me.
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For a hypermiler it's absolutely zero, it might even be negative.