Anyone UNDER 21 - MPG that is

[billyharless]

2008 Solstice NA and I get between 21-24 as a daily driver. I commute into DC 4 days a week.

[Celt03]

I get about 26mpg around town with my RL & I am in stop/go traffic all the time. I have never had it down in CA.

But I do have a couple of reference factors.
With my GTP I get around 23+ mpg living here but in California I only get about 19-20mpg.
My husband gets about 17-18mpg with his ZR2 but in California it drops to about 14-15 mpg.
Since the traffic situations are similar - I would definitely say that there is something different about the gas there.

And I do not rely on the DIC - I calculate it.

[SkyMan 08]

Originally Posted by Celt03

And I do not rely on the DIC - I calculate it.

one thing the DIC measures the actual amount of fuel used. when you calculate it you enter many error factors and each one multiplies the error. like is the pump accurate? are you parked level every time you fill? are you sure you are filling to the exact same level every time? All those questions along with evaporation and spillage make manual calculations inaccurate..The computer knows how long each injector is open and the fuel pressure so it can calculate the exact measurment of fuel going into the engine. (all part of the engine management system). Really it is hard to beat the actual measurment the DIC gives you, I guarentee they will never be the same...the DIC will be a more consistant measurment.

[Boomer]

Our average varies somewhat, (depending on who drives, and etc.) and I am somewhat of an 'agressive' driver...but our averages are typically...

Hovering around 23 mpg bee-bopping all around town with chores and etc. Anyone close to Charlotte knows the hellish traffic at times.

Getting around 23.5-24.5 horsing around in the hills, and railing the car at Deal's Gap and other locales.

Flat tracking down to the beach & back, we are usually in the mid 30 range.

If you are not getting at least close to those numbers, then you either have forgotten to reset your system, or you have other issues. Check your tire pressures, reset your trip system, and then measure accurately. Find a reason to get out, and test it at other locales. If you still see consistently below 22, you either need to loose the weight in your right foot, or have the car checked.

[MidniteBlues]

Originally Posted by SkyMan 08

one thing the DIC measures the actual amount of fuel used. when you calculate it you enter many error factors and each one multiplies the error. like is the pump accurate? are you parked level every time you fill? are you sure you are filling to the exact same level every time? All those questions along with evaporation and spillage make manual calculations inaccurate I disagree, with the testing I did over a period of 10 months, manual calculations consistently and each and every time showed better mileage than the Drivers Info Center. ..The computer knows how long each injector is open and the fuel pressure so it can calculate the exact measurement of fuel going into the engine. (all part of the engine management system). Really it is hard to beat the actual measurement the DIC gives you, I guarantee they will never be the same That is for sure and I can guarantee they will never be the same....the DIC will be a more consistent measurement.Consistent? not so, IT IS however a good "guesstimate on what is "currently and most recent driving "conditions have been.

Sorry but I agree with Celt03 as far as if you want "actual & truthful" numbers based on reality numbers. Like the manual says on page 145, "The fuel economy data to determine fuel range is an "average" of recent driving conditions. As your driving conditions change, this data is "gradually" updated. The fuel range mode cannot be reset". In addition, page 146 under ECON, states, "This mode shows how many miles per gallon (mpg) your vehicle is getting based on current & past driving conditions". IF you do not reset when you fill up, it "will be continually updated each time you drive". In no way will that math tell you "EXACTLY" how many miles per gallon per tank your car is REALLY getting. It is an "estimate".

In my monitoring, using the same gas station, same pump, (which by law MUST be accurate down here, they are inspected), level ground AND using 93 Octane Shell premium fuel, consistently showed the dic to show "LOWER" miles per gallon than the "REAL" numbers showed after each and every fill up. The errors were shown to be from as low as .1 (which only happened 3 or 4 times, and would not be at all bad if it happens all the time AND would prove your points, however my real life tests shows that DIC is only a guide) to a high of 2.54mpg off. The DIC was consistently showing worse mileage than reality. It IS however a good gage to use, when it is the only thing you have. Your mileage may vary obviously, quality of gas IMO will effect your mileage. Look at all the California drivers here complaining about their crappy fuel out there..and their lousy mpg numbers..

[Rob the Elder]

Our computer says that we have accumulated an average of 23.9 mpg.

I find it interersting that My GTI at zero throttle while coasting down hill shows an instantantanious mileage of 00 while the Sky under the same conditions shows 99 mpg.

I dont have a lot of data on the Sky yet, but I have proven to my own satisfaction that my GTI gets its best mileage at 82 miles per hour. The drop off is minor up to 92 which is where I set the cruise while crossing Wyoming. Its clearly driven by engine efficiency and aerodymanics. I am looking forward to doing tests with the Sky to see where the MPG peaks.

Also, the GTI is governed at 130 mph which I can verify through personal experience. The data I have on the Sky is that it does not have a speed limiter and it is drag / HP limited at 136 mph. Anyone have any data on that?

[kphelgerson]

With my 2008 RL, the worst I have gotten on the DIC was 25 and the best was 36...but that was only for one leg of a journey on highways mostly. And I was coming down from Grand Rapids to Richland, so as we all know, going from North to South you can coast some
Just Kiddin...it's mostly flat. Watch that speed issue. It doesn't take much to worsten your mpg with too much speed. You can become a fanatic about this, but somewhere around 35 mph in 5th on my manual gets the best mpg, but who can stand that for long? Over 40 mph all vehicles I know add much drag with increasing speeds, and you should see mpg fall off.
Are there any other brave souls out there who like me use mid-grade or regular gas? I have hardly ever used premium gas. Mostly mid-grade which a local station (not a high-tier place) sells for the same cost as regular quite often.

[JRinKY]

MidniteBlues : Sorry but I agree with Celt03 as far as if you want "actual & truthful" numbers based on reality numbers.

Sorry, but I agree with Skyman 08.

Page 145 is referring to the Range display, not the Economy display, and Economy is not indicating miles per tank, it is indicating miles per gallon, which can be very easily calculated.

I have compared the DIC to my calculated mileage, and if I am consistent with the same pump at the same station every time, I get the same mileage both ways. I have found that it takes a very small variation in filling the tank to get a discrepancy in calculated mileage. I have also found that over multiple fillups without resetting the DIC, variations tend to average out.

As far as mileage from different fuel grades, my 2.4 does not seem to care what fuel I feed it. It gets 24 MPG in a mixture of city and highway driving.

I used regular grade Chevron and Shell for the first year I had the car, but after reading reports here about better mileage with premium, I switched. The first tank did, indeed, give me 28 MPG, but after the second tank it dropped back to 24. I am now using mid-grade and still getting 24 MPG. My driving style and patterns have not changed.

[LostKnight]

I can't give you any clear numbers to validate this, but you should check out your performance and happiness with the Conoco gas, even over Shell's gasoline.

I've been told by people directly related to the making of the additive for both companies that the Conoco blend is slightly better than Shell's.

Again no real proof, just relaying information gotten straight from a man who designs gas additives for a living.

[Celt03]

My DIC is usually within a mile (+/-) of the manual calculations. And I always do a fill-up & I am the one who pumps the gas.

As far as freeway driving - that is not calculated on mine because she has only done a few short freeway hops on very rare occasions (usually between 3-6 miles).

As far as the gasoline - I ALWAYS use the premium gas at either ARCO or Chevron. There are no Conoco gas stations around here. And I avoid the Shell stations in my town as I have had several bad experiences with crud in their gas plugging up the fuel filters on my other vehicles.

And as I was saying before - the traffic in the areas of CA that we drive in with our other vehicles are almost identical to where I currently live and my driving style does not change at all.

[SkyMan 08]

Originally Posted by MidniteBlues

In my monitoring, using the same gas station, same pump, (which by law MUST be accurate down here, they are inspected), level ground AND using 93 Octane Shell premium fuel, consistently showed the dic to show "LOWER" miles per gallon than the "REAL" numbers showed after each and every fill up. The errors were shown to be from as low as .1 (which only happened 3 or 4 times, and would not be at all bad if it happens all the time AND would prove your points, however my real life tests shows that DIC is only a guide) to a high of 2.54mpg off.( How can you prove though that your figures are not off? Skyman) The DIC was consistently showing worse mileage than reality. It IS however a good gage to use, when it is the only thing you have. Your mileage may vary obviously, quality of gas IMO will effect your mileage. Look at all the California drivers here complaining about their crappy fuel out there..and their lousy mpg numbers..

For one thing, your figuring only goes down to a .1 of a gallon, the computer figures in every squirt of gas that flows through the injectors.
Your comment about page 146 is averaged only until you reset the Econ setting, then it starts at 0, and that is what you do when you fill the tank up and then check the mileage, you figured your mileage over the past operating conditions of that tank of gas.... You HAVE to figure in the mileage over several tanks of gas to get a good AVERAGE MPG for your type driving. The DIC does not care if you put one gallon in or 10 gallons in because it measures the actual useage...

Here is another reason your manual calculations can be far off from the DIC....Do you compensate for the expansion of the gasoline on a hot day compared with a cold day? Do you always fill up with the gas at the same temperature? or does the temperature where you live stay constant all the time with the same tank of gasoline? So even if you put the exact same number of gallons in today as you did yesterday (the pump does not know if it is hot or cold it just measures the gallons), If the temperature has gone up 20 degrees then you have lost energy over the previous day and will get poorer fuel mileage. Vice versa if the temperature goes down your mileage will increase.
Gasoline expands with temperature and as it expands it loses a corresponding amount of energy available in each gallon.
The computer compensates for change in energy available per gallon by changing the air/fuel ratio for maximum effectiveness, that is why you have mass air flow sensors, air pressure sensors and oxygen sensors. your manual calculations cannot compensate for that factor.
As an interesting side note, in the old days with mechanical fuel delivery systems to the engine (Carburators) they couldn't compensate for energy change in a gallon of gas so they used the same amount no matter what the energy potential of the gas was. it used the air flow over a venturi to suck in the gasoline. that is why they would run better on some days than other, they were good at the temperature and barometric pressure it was when and where it was set. that was B.C.C (Before Computer Control)

to make a long story short..I trust the DIC over your calculations...

http://www.consumerwatchdog.org/reso...lUSAJune07.pdf

[MidniteBlues]

To SkyMan 08 and JRinKY both of your points have merit. My .1 calcs were rounded off, in reality my calcs were taken out to the .001 ranges.. for ex: I just rounded them out for this thread. I say use what ever methods work for you guys.. I don't track it manually anymore, I did that test just to see how accurate it was in the "real" world, and for me at least, the DIC still remains an "estimate" an "average" if you will and a "good guess" AND very much usable. Also, yea, gas does expand, thats a fact, down here in Florida it was always in the "expanded" or hot stage when I did the manual thingie.. As an example of 1 fillup, I put in 5.637gallons of fuel in that case I got 25.545503 mpg in my calcs and the DIC gave me 23.5mpg.. So yea, variables wil always be involved, some tanks I did better, in others I did not. Bottom line was, manual calcs always gave me better mileage whether the .1 used, or the 2.0+ mpg gallons above..

[SkyMan 08]

I was just thinking about the threads on here that complain about the accuracy of the Sky's guages/readouts....
then I remembered one of the biggest complaints about the Sky when it first came out was the lack of guages...
Ironic huh....

[turbo53]

With my RL:

Getting about 22 MPG city driving to and from work.

On a recent highway trip, about 380 miles round trip, got 33.

[SkyMan 08]

I have been dissapointed with the mileage on my 2.4 automatic, I can only get around 26 on the highway, and overall I am averaging 22.3 for the last 1000 miles. My 2007 2.4 5Speed would get 31 on the Highway and overall get 27 over 1000 miles...
Oh well by the way I have an 07 HHR with the 2.4 Automatic and get 32 on the highway....

[Rob the Elder]

After accumulating several hundred miles on both the Sky and Sol, I find it interesting that both are showing the same DIC 28.9 miles per gal as of last night. The wife drives the Sky daily to work, mixed freeway and some city. I drive 25 miles each way at 70+ with a couple miles of 45 mph.

I am currently observing that the Sol mileage goes up as speed increases to a bit over 80 mph. Its getting on the order of 30 MPG at that speed / rpm.

I have not seen any mention of the correlation between the Econ number (MPG measured) and miles to go. I believe that the miles to go number has built into it some margin so people are not having to walk to the gas station and to account for inaccuracy in the system. If the Econ number is used to calculate the miles to go, and the miles to go has margin built into it. then the algorythm used to calculate the Econ number may be conservative such that the margin shows up in the miles to go number. Without actually looking at the documentation one would have to reverse engineer the relationship.

I also have to tip my hat to the person who would actually collect data and do calculations for fun. LOL

[JRinKY]

SkyMan 08 : I have been dissapointed with the mileage on my 2.4 automatic, I can only get around 26 on the highway, and overall I am averaging 22.3 for the last 1000 miles. My 2007 2.4 5Speed would get 31 on the Highway and overall get 27 over 1000 miles...
Oh well by the way I have an 07 HHR with the 2.4 Automatic and get 32 on the highway....

Your HHR probably has a shorter (or is that taller ?) final drive ratio.

Rob the Elder : .........I have not seen any mention of the correlation between the Econ number (MPG measured) and miles to go. I believe that the miles to go number has built into it some margin so people are not having to walk to the gas station and to account for inaccuracy in the system. If the Econ number is used to calculate the miles to go, and the miles to go has margin built into it. then the algorythm used to calculate the Econ number may be conservative such that the margin shows up in the miles to go number. Without actually looking at the documentation one would have to reverse engineer the relationship.

Between here and the Sol forum there has been extensive discussion about this. There is also a note in the owner's manual about the method used for the range calculation.

The displayed mpg is the aggregate calculated since the last reset, and would not be usable to calculate range, so the computer uses a "recent" mpg average to calculate range. Any correlation between the displayed mpg and the displayed range would be entirely coincidental.

[SkyMan 08]

Having had several cars with the readouts of Miles To Go And The Econ (average mpg), I have come to this conclusion...
The miles to go is based on previous driving conditions, not necessarly corresponding to the average MPG you are showing at the moment on your DIC, the Miles To Go may or may not be accurate according to your present driving conditions, if you have driven partially in the city and then switch to highway it will show less miles to go than if you did all highway driving, and of course vice versa, if you drive the highway for a while then switch to the city driving it will probably show more miles than you could actually go in the city...
Econ readout is the Average MPG since last time it was reset in the DIC. The miles to go cannot be reset, so it will not be as accurate... (uness you consistantly drive the same) it takes a running average of MPG and average driving conditions along with the current fuel level readout (which if it is not accurate your miles to go will not be accurate) over a unknown (at least by us) number miles to calculate the miles to go, for example I just took a trip in my HHR, it was showing I had driven 340 miles on a little more than 1/2 tank of gas, the miles to go said I had another 200 miles before I could fill up, but then driving in town I had to fill up after I had only gone another 50 miles ( I fill up between 1/4 and 1/8th tank I don't wait for the low Fuel Light) and the miles to go showed I could still go another 100 miles. Showing it was it was heavily using the traveling on the highway for it's calculations and had not yet fully adjusted to the mpg I was getting in city driving...While my Econ MPG dropped from 32 down to 31.5, When I filled up the HHR it calculated out to 31.7 mpg.. within a close margin of error between that pump cutoff and the one I originally filled up at.

So the Miles To Go is just a suggestion, not a rule to follow, just go by the gas guage... when it says low fuel, (then the miles to go will only show "LOW FUEL" and not give a number) or when you are getting uncomfortable, stop and fill up. I do know when it says low fuel, I better stop very soon...

[JRinKY]

SkyMan 08 : Having had several cars with the readouts of Miles To Go And The Econ (average mpg), I have come to this conclusion...

Your conclusion is basically what is described in the owner's manual.

Since the Range to Go assumes running the tank empty, and since fuel gauges are not normally very linear, making a judgement about Range to Go accuracy based on partial fuel gauge readings is an exercise in futility.

I have never had a vehicle that read 1/2 tank when the tank was actually 1/2 full. And the lower half is always smaller that the top half.

You are exactly correct that radical changes in driving style can fool the Range to Go calculation, but it is still a reasonable guide. The numerical readout changes to "Low Fuel" at 40 miles, probably to keep some bozo from complaining that they ran out of fuel when the computer said that they still had a mile of range left.