The only reasons I even bother to track my MPG is to look for problems creeping up on me. If the MPG changes suddenly it means "something" is going on.

 

So I was testing out the miles till empty reading on the DIC, left work in the city and the readout said 20 miles till empty. Haha, got two miles down the road and the HHR shut down. Luckily, I was literally across the street from the gas station...unfortunately, because I recently removed my stuff from the back to take out some interior panels...I didn't have my gas can with me...lol! So...had to spend $10 for a 1 gal. gas can to hold $3.50 worth of gas. Just my luck...but in all fairness, it was my own fault...haha, oh well.

Now I know...haha!

 

My average indicator is consistently about .3-.5 mpg lower than reality.. and I average 27.5-29 mpg in mine depending how I drive. Straight highway without stopping it will do 32-33 mpg.

 

My 2008 LT stops displaying "miles to go" at around 1.9 gallons left (50ish miles to go).

 

Mine is the same. I really start thinking about getting gas at that point.

 

Thanks, Doc.... all that makes perfect sense. So, we are then to ignore the Instant Average completely, as it is always wrong, yes ? Lucy usually shows 40-45MPG INSTANT on 4-lane semi-rural Dixie Hiway at 55MPH with the cruisey turned on, but her AVERAGE MPG has never gone above 24.6MPG (which includes Dixie as well as 2 weeks per month of interstate at an average of 50MPH for 60 miles per day withOUT the cruisey on). We're still trying to get a handle on her actual MPG since we only bought her 3 weeks ago, with 34,000 miles on her. We got an HHR with the hope that it would actually get the 32 or so MPG stated, at least on the interstate.... the (traded-in) 2002 Dodge Grand Caravan V6 was killin' us on fuel !

 

Just make sure you reset the MPG reading after each fillup. Also use the old paper and pencil method to doublecheck the computer.

 

Mine is off by exactly one mile per gallon both times I have checked it. Last time it said 27.5 mpg but I really got 26.5.

 

The last time I ran mt tank low, the DIC went to low gas once I got to less than 40 miles cruising range. The DIC on my 06 has always read lower than the calculated value.

 

i have a 2010 2.2L Lt. i get between 29/34mpg average. tire pressure, air filter, weight of vehicle, highway vs. city driving all come into play when calculating mpg averages, just swapped out factory air filter and plugs. vehicle has 71k on it. do alot of highway driving. could have waited a little longer on plugs, but decided to change early. engine runs so smooth! i just do the math myself divide the number of miles driven by how many gallons i put in the tank. so far so good. i love my hhr!