firemangeorge

I check mine manually every time. Fill up, get the receipt, figure it on the back of the receipt. Takes all of about 20 secs. extra. Takes longer to reset all the stuff in the DIC.
I also log all my gas purchases in a notebook that stays in the glove box.
Why? Because my wife says I'm anal.

A Crazy Canuck

I have done 2 mileage checks. Both times the actual mileage was a bit better than the DIC said. Very close though. Less than half a litre per 100 k off...
Also, the fuel range was pretty darn close too.

IMPALADAKID

Update:
After two fill ups, I am averaging 25.1 mpg, and the DIC says 25.3. So I guess it is pretty accurate after all.

F-16C

Granted I have only filled my 2011 HHR 4 times since I got it. However, I have been keeping track of mileage in all my cars since 1979. Back then we did it the old way, miles driven devided by the gallons put in at fill up. my DIC is 1.0 mpg off to the high side. Filled yesterday and the DIC read 28.9 but miles driven devided by the gallons put in at fill up and it was 27.9 . How much of all this really matters? I do not know. However the one thing I do know is ,at the end of the day is how much you put in the tank and how much you pay the man behind the counter. And living here in California at $3.93 { and going up} a gallon for 87 octang, it matters how much I pay the man at the counter. So the game continues

Uplink

I am a bit of a data freak, and I always record mileage in a spreadsheet along with the number from the DIC. Over 37K miles and 135 fillups, the average difference between the two is 0.8 mpg or about 4%, with the DIC overestimating mileage by that amount on average for my 06 LT1. I disagree that "The computer does what the driver does, only with far more accuracy" because the DIC estimates the amount of gas used by reading the fuel tank sending unit, which is not as accurate as the meter on the average gas pump.

Blue Beast (aka Boydie)

Hello

My 2.2 2008 Panel reads 32-34MPG on the Eway every time I travel it and I think it is accurate. I have a free breathing air filter on the car and it does make a difference. Now if I could keep my feet off the accelerator in the city.

(The above is not an average. I should say I have never checked it myself).

Boydie Back in the Saddle...................

rkstevens

I just did a 575 mile trip, where after my fill up at 454 miles, the DIC read 32.2mpg, and calculated was 32.498, so I would say that it is pretty accurate.

As far as the argument about the accuracy of the fuel pumps vs. the vehicle injector in measuring the amount of fuel, there is one big factor that is not taken into consideration: temperature. Gasoline expands (like everything else) when it is warmer, so a physical liquid gallon at 70 degrees contains less energy than a physical liquid gallon at 40 degrees. At the refinery and marketing level, all fuels are sold based on their amount at 60 degrees Fahrenheit. While this adjustment is made at the pump for those in Canada, in the United States this is not the case.

donbrew

Costco just settled a class action suit for selling gas by volume (not adjusted for ambient temp) not energy content . Now they must replace all of their pumps to adjust to temp.

636mullet

I've checked mine a couple times and the DIC is about 1 MPG high. Not a big deal. One thing to think about is the DIC doesn't account for idling. So if you remote start or get stuck in traffic a lot your gas is burning but you aren't covering and ground.

-636

Old Lar

I reset the mpg DIC at every fill up and I found the DIC reads low by 1-2 mpg compared to hand calculated results. It is a useful tool to estimate mpg. When I'm on the road, I have notice that miles driven plus miles range left equal 500 miles I'm getting good gas mileage.