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Old 09-28-2012, 09:29 AM   #35 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 53.47 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
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Ouch!

Since we know taking the electrical/alternator load off the engine is absolutely going to save fuel, I would say those savings were off-set by increasing other loads:

1) the weight of the solar/battery system (probably a relatively small impact), plus,

2) the added aerodynamic load of the panel mounted on the roof which increased frontal area (A) and drag coefficient, (Cd).

Aero losses were probably a relatively larger impact compared to the weight gain.

It's discouraging to do all that work and not see the effect you were hoping for (been there, done that!).

Thanks for reporting unexpected results though. It'll help the next person considering this type of mod.
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