How accurate is the MPG average on the readout? I have not performed the mathematical method yet. 09 Crew Hemi.

 

Hopefully its more accurate than the thermometer lol. My mpg read out seems to be fairly accurate over an entire tank just doing the math upstairs after having filled up at the same pump twice. I don't know what its doing sometimes though. It may be the MDS kicking in and out. When I first got the truck, I was showing it to a buddy. I wanted to show him the evic so he jumped in the drivers seat and I turned the key to on (did not start it). While we were looking at it, the mpg increased by .2 mpg while sitting in the parking lot.

 

I was using 87 octane gas, and when I filled up with 89, it immediately (drove less than a mile) read 1 mile more per gallon. Now, how smart is this machine?......LOL

 

I have less than 2k on the truck. I have gotten has about every 200-250 miles. I reset the mpg after each fill up. The evic mpg has been either low or high by 2-3mpg, when compared to actual calculations. It was basically correct only one time.

 

I have 2100 miles on the truck and I reset whenever I fill up.

I'm consistently about 1 mpg high on the computer readout compared to hand calculation.

Last tank:

Computer: 14.5
Hand: 13.54

 

You never really know much closer than 1 mpg unless you are hooked up to flow sensors, or if you were to measure out a set amount of gas and run until empty. Something as simple as filling up in the early morning the first go around and filling back up in the late afternoon will skew hand calculations. I think the problem is the way the computer avg.'s it out. Probably about the only thing it's really good for is trying to figure out what habits, mods, etc. get you more mpg's. I had a 2003 Dakota that if you reset it while going down a hill at 70 with your foot off the accelerator, it would come back up and say like 50mpg or better.