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Old 05-14-2022, 03:40 AM   #276 (permalink)
Drifter
EcoModding Apprentice
 
Join Date: Apr 2022
Location: California
Posts: 166

Cx9 - '18 Mazda CX9 Grand Touring
90 day: 31.41 mpg (US)

Prius - '10 Toyota Prius III
90 day: 57.8 mpg (US)

Tundra - '00 Tundra V6 long bed base work truck
90 day: 19.4 mpg (US)
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Quote:
Originally Posted by Phase View Post
so for the coast down testing, pretty much i find a spot and go up to say, 70 mph, then put in neutral and just ride the car till it stops, and mark the spot? then do the same thing with the aero mod attached and see if my range increased?
Yeah pretty much. I would put out a cone or something to mark where you want to start coasting. Then drive up to it with your cruise control set at whatever speed. Cancel cruise & coast in neutral as you pass the cone. Rolling to a stop is ideal, but you might also be able to roll to another landmark and note the speed.

Then circle back and do it again. Use the "resume" function on your cruise control to try and use the exact same starting speed. I'd probably do 3 tests unmodified and 3 tests with the modification. That should be enough to show whether the change provided a large improvement.

You might also see about using an OBD2 logger to log your speed. That would probably be best because you could compare the speed vs time curves to see if any random bump or gust of wind suddenly changed the slope of the curve on one run...
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