When I bought my 2.2 panel, I did so not to go fast but to look cool getting there. Decent fuel economy would have been nice though. I see the posts 30+ mpg and marvel at the possibilities. When I drive like Granny going to church on Sunday I get 29 with a pencil. So I usually drive it like I want and only fall to the 26-28 range. I may change my intake this year. Bloggers say that does make a difference.

 

Highway MPG i.e. all at 55 MPH should get around 30ish. Any traffic involved in your drive to church will drive that down to 26 ish.

 

Things are getting interesting and not in a good way. I filled up today with the DIC reading 21.9. When I did a manual calculation, 18.9! WHAT?! You gotta be kidding!

On to the next experiment: clean MAF and see what that does.

Maybe it's time for a survey. Anyone game for that? I hope so because I'd like to get to the bottom of this. If you would here's what I would like to know...

Year
Motor (2.0, 2.2, 2.4)
Transmission (auto, 5 speed)
Climate (cold, warm, wet, dry or various)
Driving (flat, hills, country, city or various)
Style (aggressive, easy or various)
DIC readout (what does it say right now)
Manual calculation (would be very helpful)

It would be fantastic if you volunteer. Please do not embellish or provide any other info.
Also stay with the format so we can get a clear understanding of what may be going on. Post
your stats here on this thread. With enough data we can spreadsheet this and see what
answers we can get. Thanks!

 

This type of survey has been done, informally, in ALL the threads and posts made regarding, "Help, I only get XX MPG at 110 MPH", "Somethings wrong I get 40 MPG in the city", etc. etc. You could read all those.

But seriously, you will gain very little accurate info, IMO....i.e., your city driving is different than my city driving, your 70 degree temperature day is different than my 70 degree temperature, your average highway MPH is different than my highway MPH.

That is why ALL manufactures use the same computer driven road course for city and highway mileage ratings. Although, the vehicles are "driven" (on dynos) by humans, the software indicates specifically when the driver is to accelerate, brake, coast, idle, etc. and for how long and the type of pedal pressure application. This was agreed on and mandated by the Federal Government. It brought increased uniformity, honesty and validity to the MPG ratings on the window sticker.

Oh, I forgot to indicate......the test dyno cells are in a barometric chamber, which controls temperature, humidity, pressure, etc.

 

we would have to correct for altitude, air density, squirrel fur on the bumper, bugs on the headlights all kinds of factors effect mileage, I just know its much better on the highway in the spring than stuck in snow and traffic in the city during winter.

 

Exactly Oldblue.
And mine stays pretty much the same year round because we don't have those extreme weather changes down here on the coast.
Well, except for those high humidity, 99 degrees summer days.

 

11, you're really overthinking this, there are too many variables to even make the data quantifiable.

I think that if you just relax a tad, and get to the warmer weather that is coming as spring draws near, you'll see your mileage improve once you break free from the Arctic temps you've been seeing.

HHR mileage can be all over the place, and as the EPA says when vehicles are given their fuel economy numbers, "You're actual mileage may vary".

 

^^^^^^^^^^^^^^^

Obsessive would be more like it


Oh, and for what it is worth, your hypothesis regarding how MPG is calculated appears to be incorrect. I found this 2011 article on Edmunds.com after they found discrepancies in dash readouts and manual calculations. Make from it what you wish.

Roger Clark, senior manager of GM's energy center, explains that the fuel economy gauge makes a calculation by counting the number and duration of pulses made by the fuel injectors as they squirt gasoline into the combustion chambers of the engine. The onboard computer system divides the distance the car travels by this estimated fuel consumption.

Clark says the gauge is "dead nuts accurate" — if you consider all the variables at work during driving, including temperature, driving conditions and driving style. The biggest fluctuation occurs because ethanol, which is blended with gasoline in varying amounts, contains less energy.

"When you fill up, you are paying for a gallon of gas, but the energy in that gas varies significantly," Clark says. This means that while the car's computer assumes the gasoline is providing energy to drive a certain distance, the fuel might have less energy and not propel the car as far

Here's a link to the article in entirety.....

http://www.edmunds.com/fuel-economy/...s-fibbing.html

 

Today I did over 700 miles 98% at 72 MPH cruise control on ambient temp was in the 50s F. to my surprise I got 31.5 MPG. 2 weeks ago 700 miles at ambient temps in the single digits got 25 MPG.

 

This is the point exactly.

Where I am (Northeast USA), the temperature is up (40's) and so is my mileage. Nothing else has changed. I use the same gas, same gas station, same gas attendant, same gas pump. Same driving, same routes, same roads, etc. Nothing has changed except the temperature. I did clean the MAF at the beginning of the warm-up so I can't isolate the increase to temperature alone. Although I suspect the MAF cleaning didn't do a thing.

The survey is intended to try to isolate the cold weather, poor gas pattern in some way. Is it a particular year, motor, transmission, climate or a combination of things that is causing the loss in efficiency? Most importantly, is there a fix?

It's ok if there's not any interest in the survey. It does require a commitment.

Regarding being "obsessive". I disagree. Although maybe I have not been expressing myself correctly (Sorry, I'm not one to use emoticons).