MPG's...?

thompsonCRD · **Posted:** Sun Sep 25, 2011 8:46 pm

My wife mostly uses our CRD (probably 60/40 hw/cty), I usually only drive it on weekends. I reset the trip and MPG steps in the EVIC about 1500km ago. I checked today while I was driving it and it's reading 8.4L/100km (27.6mpg)!
Sounds awesome, but is this accurate do you think? I recall reading elsewhere on here that the EVIC is not great at calculating accurate MPG's.
On next fill-up I plan to hand calculate, but for now I am curious how far off it could really be.

cgass · **Posted:** Sun Sep 25, 2011 9:26 pm

I'm not sure how accurate the EVIC is...but I do know other ways to accurately track your MPG's. Try fuelly.com on the computer or if you have an android phone there's an app called aCar which is really great. It tracks everything and is free. I've been using it for 2 years.

Ajamant · **Posted:** Mon Sep 26, 2011 12:41 am

That would be some great overall milage and could be accurate. I've hand calculated 33mph highway milage.... But that was 65mph on a long road trip. As long as you are having no mechanical issues and your easy on the skinny pedal, your milage will be great.

papaindigo · **Posted:** Mon Sep 26, 2011 9:43 am

The EVIC is, at best, an "indicator" of mpg and accuracy or lack of accuracy is highly variable especially with "snap" readings. I've had personal experience with EVIC accuracy on a stock CRD ranging from close to dead on (within 0.5 mpg) to wildly off (4mpg over actual); the early GDE EcoTune added to the error factor (that almost dead on went to 7mpg over actual); current GDE EcoTune brought accuracy back to something like that of a stock CRD. Somewhere either on this forum of the GDE forum Keith commented on how the EVIC calculates mpg and why it's not accurate and why it is difficult to make more accurate. Adding to the issue is inherient error in the odometer with stock tires; change in tire diameter due to wear; and odometer error added by use of new tires of different than stock diameter.

Bottom line is the only way to get an accurate handle on your mpg is to fill the tank as full as possible (e.g. fuel visible in the filler head - obviously be careful not to spill); drive a known distance (do not depend on maps, hwy mileage markers, or odometer - use a GPS) preferably at least 200-300 miles. When done fill the the same level (again don't spill) and hand calculate the result. Compare to your EVIC and odometer to get a decent correction factor for future reference.

Depending on your driving style, speed, terrain, ambient temp, use of AC, and whether your termostat is functioning correctly the normal mpg of a stock CRD in ca. 18 mpg in town and ca. 27 mpg on the hwy. That's assuming stop and go traffic with top speed 45mph but average more like 25mph at best vs. ca. 62mph or 1800 rpm on the hwy. With the GDE EcoTune the equivalent figures are ca. 22mpg and 32mpg. Before anyone jumps on me these figures are based on my personal experience GPS corrected/hand calculated and may be better or worse than what others experience.

boilermaker2 · **Posted:** Mon Sep 26, 2011 2:30 pm

I agree with papaindigo. However, I just use my odometer and do not account for tire size, odometer error, etc. While possibly not helpful from one machine to the next comparisons, it does reflect driving style, type, weather and serves as an indicator that something needs to be checked if mileage falls off (or increases) and cannot be accounted (ie. the T-stat failure will gradually kill mileage, hard to see the impact if not monitored).
Boilermaker2

MPG's...?

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