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Old 01-30-2009, 10:13 PM   #1 (permalink)
Renaissance Man
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Join Date: Jan 2008
Location: In the Northeast dreaming of the Southwest
Posts: 596

Aegean C - '17 Honda Civic LX
90 day: 41.77 mpg (US)
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Speed/mpg testing

I did some speed/mpg testing on my car recently. '97 Ford Escort, 2 liter 4 cylinder, 4 speed auto. Just a few minor aero mods. The speeds I tested were 40, 45, 55, 60 and 65 mph. I couldn't find a good road to do 50 mph so I left it out. I didn't bother to do any slower speeds because the torque converter won't stay locked below about 37 mph. I recorded the mileage with the SGII. To get the data I did three runs back and forth, getting the car up to speed, setting the cruise, and re-setting the trip meter. Roads were as level as possible, but the two way runs should eliminate any error from grade. Engine was at operating temp before making any runs, and electrical load was minimized (no lights/radio/hvac). Ambient temperature was 17*F. I'm sure these numbers would be significantly higher in warmer weather but that should not affect the slope much.

40 mpg - 40 mpg
45 mph - 38.2 mpg
55 mph - 36 mpg
60 mph - 33.4 mpg
65 mph - 31 mpg

Anyone have some good graphing software?

The data from 55 to 65 is pretty much in line with what I have seen on graphs for other vehicles, but it still drives home the point of the huge FE hit taken at speeds above 55 mph. I was a little surprised to see the significant decline from 40 to 55 though. Am I missing anything? Questions/comments?


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