Best I ever got was 48 mpg with a Tail wind pushing us along @70mph on a flat road for about 5 minutes

http://www.youtube.com/watch?v=iLyDdDWU9fU

 

Grumpee looks more like 76 - 77 MPH unless your speedo is like mine and read a bit high?

 

Yeah you're right it was around 75 mph...I'd forgotten about it...we were on our family pilgramage to the Holy City of Vegas

 

Just a tad over 60 in warm weather, around 57 when it is colder.

 

I still say we need a six-speed, stretch'em just a little more, lotta turnpike for me and I like to run about 80, just don't like peggin that high on my tach

 

I use Ecoroute on my Garmin 265WT to see how "efficient" I am. With the cruise control set around 105 km/h the Garmin shows a 99 for my efficiency. Ecoroute was included in the software that came with my unit but may be added to some other models of their products just by downloading and installling it.

http://www.garmin.com/garmin/cms/us/services/ecoRoute

According to their news releases they are adding Ecoroute HD to the lineup of their toys. As I understand what the unit does. You plug the unit into your cars computer and it puts the data on your Garmin's screen through a Bluetooth connection.

http://ces.cnet.com/8301-31045_1-10425380-269.html

No I don't work for them or receive any compensation. Just a guy letting others know about a new product they may find helpful!!!

 

On my 2009 LT Automatic I just returned from a 200 mile trip, mostly Interstate. I saw what the instant reading was, but checked it after filling up and got 32.5 at 67 mph actual. The milage on the car showed 30.5, so you need to measure actual.

_______________________________________
2009 HHR 1LT 33,400 miles now.

 

^^The digital average will always be more accurate than your hand calculation. There are far to many variables in hand calculating. The pump shutoffs are always different (pump to pump), the angle of the spout effects shutoff, fuel temperature, type of fuel, decimal places held, etc. It goes on and on, unless you've modified your fuel injector tables your pcm is monitoring it far more precisely than you are calculating it.

 

For 63000 miles on my 06 HHR this is what my mpg statistics. The 21 is an outlier as I may have not filled the tank properly.

This was 186 tanks fill ups of gas.


Average 30.57
std dev 2.907
max 38.03
min 21.81

 

That makes pretty good sense that it could monitor better than I can figure with the tank getting refilled to different levels.

I almost always fill my tank at the same pump at the same station to about the same level of clicking every last ounce I can get in there.
I'd consider myself pretty damn good at getting as close to the same amount in there every time.
It usually is within 1/2 MPG as what the dash says.
Today I was actually surprised at it getting so close to the paper/pen/division method.

I filled it with 13.1 gallons at 431 miles with
AVG MPG at 32.8
Paper pen came to 32.9 MPG

Fuel Range was 567 Miles - Yeah baby!

9¢/mile beats the crap out of the 16¢/mile I got with the POS Eclipse
POS GSX - 100 miles cost $16
HHR SS - 100 miles costs $9
I've saved $2275 on gas with the SS and actually get to spend time driving it instead of always fixing it
Also saved about $150 on oil changes.
I guess I can afford that cargo trailer after all!

I usually drive within 5 MPH of posted speeds but let it roll as fast as it wants down steep hills unless I'm approaching a blind or populated or likely-to-be-a-cop-there area.
I usually give it a boost run or two per tank but not this time.

Must be getting old or something, I used to play the MPH game, now it's the MPG game.