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Old 11-04-2009, 01:44 PM   #1 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 12,537

Blackfly - '98 Metro
Team Metro
90 day: 67.07 mpg (US)

ForkenSwift - '92 Metro EV
90 day: 125.37 mpg (US)

U.F.O. - '00 Insight
Team Honda
90 day: 85.75 mpg (US)
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Exclamation Friendly reminder: CHECK YOUR TIRE PRESSURE! (It's getting colder in the north!)

I'll admit I don't do it regularly enough.

But holy cow, I had a rude reminder to check my tire pressure this morning. I hadn't measured the energy usage of the last half dozen or so charge cycles in the ForkenSwift until last night's charge, and this one was awful.

396 Watt/hours per mile. One of my worst ever, in the 70+ cycles I've recorded. (Works out to about 85 MPGe using BTU equivalence - which is pretty lousy for an EV of this size.)

(For comparison, my "lifetime" energy use is 288 Wh / mile. That's measured at the wall (Kill-a-watt), from data for 70 charge cycles, and includes summer and winter driving - more summer than winter, though.)

So I checked the tires, and sure enough a couple were well down, ~13 lbs below where I normally have them. There were other contributing factors to the bad performance, but the tires were a big part of it.

Weather's getting colder (for those of us in the northern hemisphere)... So check your pressure!


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www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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