mpg

[dhall0014]

Ok hwy mpg is a big deciding factor for getting this car or not. Through my research on other boards I have noticed people are saying that they are getting better than the 15/24 on the sticker. I assumed this would be true but i also saw claims that with a tune some people were getting 28+ on the hwy. I think this was with the VMS 93 tune. My question is if you can stay out of the throttle what kind of mpg are you guys seeing with out tune and with tune. Also are the increases with a tune pretty much the same or will i get a different result with different tuners. Also when you all figure your mpg are you going off of the computer or are you going off the odometer when you fill up. Thanks

[Cobra]

I recently installed a New Era cold air intake and Vector Heat Soak Reduction Kit. With no other mods. Prior to the install running regular gas I was averaging 16 mpg in town driving. After the install and running premimum I am running 19.9 around town. This of course is keeping my foot out of it with the exception of one teaching lesson on a honda civic. I suspect you could see good gains not only in town driving but hwy as well.

[wreckwriter]

19.9 in town??? How are you measuring that? That's totally unrealistic in my experience. 15 would be shockingly good. My own is more like 10.

[09PBMGT]

Without the tune..... I was getting between 17-18 mpgs. Thats mostly city, some cruising speeds 55-65. I just uploaded the VMS tune (91 octane) today, so i'll post my mpg after the first or second full tank. I'm hoping to see 19-20 mpgs. I'm sure that I'd see over 24 on the highway. I need to take a road trip. Waiting for the cool weather.... it's still 105 out here!

[Cobra]

I guess I really am keeping my foot out of it. That and it has been cool weather here lately. This is my first tank of premium so maybe it will drop by the time I get to the end of the tank.

[wreckwriter]

these cars get decent highway miles but stoplight to stoplight is pretty much shit, that's reality. if your looking for an economical car, look at the V6 version.

The good news is that gas is coming back down. I saw premium under 4 today.

[Blackdevil77]

decided to see how hi i could get the mpg today on the highway. Got up to 90, reset the dic and just coasted until something came up. average speed said 60.3 and average mpg said 45.3!!!!!!!!!! everyone was like "yeah, my ass." That's like smart car status right there. How could that be true? Most i have ever seen W/O coasting was 32.3 and that was at a constant 90. My tune is stock. For now at least :)

[Blackdevil77]

these cars get decent highway miles but stoplight to stoplight is pretty much shit, that's reality. if your looking for an economical car, look at the V6 version.

The good news is that gas is coming back down. I saw premium under 4 today.

The V6 and V8 get very similar mpg. Especially highway. Around town i'd say the difference is probably 1 to 2 mpg differance tops. Friends neighbor bought the V6. I make him jealous :thumbsup:

[johnh]

The V6 and V8 get very similar mpg.

Yes they do.

I had the opportunity to rent a G8 V6 one day and a G8 GT the next for a business trip. Mileage average was about the same, and dare I say it the GT got a little better highway mileage. My trip was about ~400 miles each way.

I got about 25 mpg in the GT cruising at 70-75. Now as mentioned above, put your foot in it all bets are off, but that's ok.

MPG is one reason I am strongly considering GT vs. GXP. Do I want .5s at the track or 4-5mpg? (I think the GXP will be a around LS2 06 GTO (6spd auto vs 4 spd (G8 better last gear), 3.27 vs. GTO 3.46, but GTO is lighter))

[GRRRR8]

The GT will a few mods is as fast as GXP and for the few like myself that are insane about power, you can be way faster and still have good mpgs and save $$

[dhall0014]

For those of you that have posted #s. are you going off what the computer is telling you your average is or are you actually calculating it yourself. I know nothing of this car but i know the system in my navigator is way off. it reads 4-6 mpg more than what im actually getting.

[dhall0014]

these cars get decent highway miles but stoplight to stoplight is pretty much shit, that's reality. if your looking for an economical car, look at the V6 version.

The good news is that gas is coming back down. I saw premium under 4 today.

Im not really looking for economical. Just around 26 or so on the hwy after tune, cai, and some sort of exhaust. I will probably be with you getting 10 or less in town with as heavy as my foot is.

Oh and im loving the gas drops. Just wander how long it will stay. In the little town of Somerset,Ky were down to 3.72 for premium a .25 drop in a day

[Cobra]

Wreckwriter is correct! After reviewing my DIC again the mileage has dropped back down to 16.6 mpg. I guess the only true test is to do the math after filling up again. Although I have no complaints about getting 16 for in town driving.

[GXPaycheck]

I have verified my DIC readings with a seperate scanner and by math. Max highway is 23mpg (70-75, cruise on), 16-18 around town.
:gc:
:ok:

[Steve]

So I always was REALLY skeptical of people claiming mid to high 20's in MPG because i'd NEVER seen that. I'm LUCKY if I average 18mpg.. I've had my VMS tune for a while and today I wasn't totally awake yet so I figured ya know what.. I'm gonna drive like a grandma and see what I can get.. lo & behold: first 20 miles of my commute 29mpg and by the time I got to work 27mpg..

So I guess it can be done, But seriously.. how can you guys drive like that?!?!? drove me nuts the entire way because I kept wanting to floor it!!
Back to driving like I stole it for me :D

[-Ray-]

Steve, I have over 12k miles on mine. Even though the company pays for my mileage, I try to make money off it.
I do spend a little of mine too, hot roddin it.

[EcoBrick Bob]

I once got over 50mpg on the street........while my wife was pushing.


I have averaged 26 at a steady 70. 24 at 75-80. 19-20 in mixed driving with stoplights. Mods after Vector ECM don't seem to have changed anything. Wife got 24.2 on way back from FL to IA for G8 miles 500-1100. Total for trip was 23.6 with an average speed of 69.5 for the 1700 mi.
Me in our Denali XL got 14.2.....

RRM

[Torqued]

After driving for 30 minutes I get 32 with the cruise on @ 65. This is on a somewhat up and down freeway, not driving across Kansas. After a few miles of city driving that hwy mpg drops into the low 20s. My city mileage is 13-17.

[GRRRR8]

You should always manually calculate mileage using 2-3 tanks to establish an average. No driving wiil be exact on every tank of fuel , so you want to know
an average that way when you mod you can reestablish a true average.

[caretaker]

I had posted this on another forum and thought it might be relevant here.
Since this post I now have 7700 miles on the G8 and the mileage is holding
about where it was when I originally posted this in May.

Original post follows:

I picked my GT up in CT. on May 10th and have done nothing to it yet.
I just made a trip from North Carolina home to Connecticut.
I started the trip home with 2163 miles on it.
I filled up at Flying J in Fort Chiswell, VA with 87 octane.
I had already done 110 miles so the car was warmed up.

Running tire pressure was 39 front and 41 rear.
Ambient temperature during the drive was 70 - 74 degrees,
with low humidity and sunny skies.
A.C. was set to 72 degrees and on auto.
Put the car in drive and got onto I-81 N.

I pulled into the Flying J above Winchester, Va. 246.5 miles later.
DIC showed 68.1 avg. speed, 27.3 M.P.G. and 329 mile range remaining.
Tank took 8.792 gallons which calculates to 28.03 M.P.G.
I was very gentle on the throttle for this drive to see what I could
get for max mileage. Other than getting onto and off of the highway
I maintained my speed between 60 and 75 M.P.H.

Got back onto the highway and stopped 276.3 miles later at the
Valero station in Port Jervis, NY just off I-84 E.
DIC showed 67.8 avg. speed, 25.0 M.P.G. and 271 mile range remaining.
Tank took 10.802 gallons which calculates to 25.57 M.P.G.
This tank I drove normally, which means more throttle, but nothing crazy.

I am quite happy with the mileage I am getting.
Most of my driving is highway. My city driving is really mostly rural roads;
not real stop and go type city. The first couple of tanks of gas were a
variety of driving and I averaged between 19.5 and 22 so I am happy with
that also.

[R.Penguin]

Ok hwy mpg is a big deciding factor for getting this car or not. Through my research on other boards I have noticed people are saying that they are getting better than the 15/24 on the sticker. I assumed this would be true but i also saw claims that with a tune some people were getting 28+ on the hwy. I think this was with the VMS 93 tune. My question is if you can stay out of the throttle what kind of mpg are you guys seeing with out tune and with tune. Also are the increases with a tune pretty much the same or will i get a different result with different tuners. Also when you all figure your mpg are you going off of the computer or are you going off the odometer when you fill up. Thanks
Got 19.1 overall on the Seattle-Portland-Seattle trip last week. 75 freeway and WOT around town. It's not possible for me to drive this car conservatively.

[dhall0014]

I had posted this on another forum and thought it might be relevant here.
Since this post I now have 7700 miles on the G8 and the mileage is holding
about where it was when I originally posted this in May.

Original post follows:

I picked my GT up in CT. on May 10th and have done nothing to it yet.
I just made a trip from North Carolina home to Connecticut.
I started the trip home with 2163 miles on it.
I filled up at Flying J in Fort Chiswell, VA with 87 octane.
I had already done 110 miles so the car was warmed up.

Running tire pressure was 39 front and 41 rear.
Ambient temperature during the drive was 70 - 74 degrees,
with low humidity and sunny skies.
A.C. was set to 72 degrees and on auto.
Put the car in drive and got onto I-81 N.

I pulled into the Flying J above Winchester, Va. 246.5 miles later.
DIC showed 68.1 avg. speed, 27.3 M.P.G. and 329 mile range remaining.
Tank took 8.792 gallons which calculates to 28.03 M.P.G.
I was very gentle on the throttle for this drive to see what I could
get for max mileage. Other than getting onto and off of the highway
I maintained my speed between 60 and 75 M.P.H.

Got back onto the highway and stopped 276.3 miles later at the
Valero station in Port Jervis, NY just off I-84 E.
DIC showed 67.8 avg. speed, 25.0 M.P.G. and 271 mile range remaining.
Tank took 10.802 gallons which calculates to 25.57 M.P.G.
This tank I drove normally, which means more throttle, but nothing crazy.

I am quite happy with the mileage I am getting.
Most of my driving is highway. My city driving is really mostly rural roads;
not real stop and go type city. The first couple of tanks of gas were a
variety of driving and I averaged between 19.5 and 22 so I am happy with
that also.

I think this is the post i saw on the other forum and i now see that you did calculate it also. It sounds like if i want I will be able to get close to 26 on the hwy. It looks like finances are looking a little better now so I guess mpg isnt going to be as big of a deal. Man I love the GI bill.

Thanks for all the post everyone

[texn884]

My 2009 G8 GT has turned 14,200 miles and has been giving me excellent mileage. The best I have got was 29 the worst has been 23. I drive almost 95% highway and set my cruise at 72-73 and I get a good 24-26 and sometimes I put my foot in it and get her running around 105 passing a few slow polks and I just smile and fly by them.

But I love knowing I have a big V 8 361 HP and can get great gas mileage and can run 140+ God Bless America for muscle cars.

I am saving money and fuel over my 2004 Chevy Colorado which got me an average 23 with the inline 5 which is a great engine and it has 382,000 miles on it and the second set of plugs and looks and runs perfect.

If you keep your foot in it no matter what car you drive your mileage will SUCK! City mileage no matter what SUCKS unless you drive a stupid smart car or a half gas half electric car.

[XXFire]

My buddy has my GXP in vegas now, he got 26.7 mpg ! @ 72 mph I think he said on the 166...

[Fatdaddy]

I got 26.2, hand calculated, on my recent 4600 mile road trip. Top speed was 117mph, average speed while moving was 69. The speeds from my gps. I generally drove 10% over the speed limit on the highway. Highest posted speed limit was 80mph.

[Seattle09GT]

I don't get any of these kinds of MPG numbers on my G8. The best I've gotten driving at the speed limit like I have an egg under the gas pedal is 25.3 MPG. A lot of my driving is urban/suburban and stop and go. I get about 16 in severe urban driving to 24 on long highway drives. I average about 18 to 19. I didn't buy this car with MPG in mind. Even with the CAI and tune I didn't see much of an improvement in MPG.

[cragspider]

On the way back from picking up my car I saw as high as 26.0 mpg @ 70mph to 24.5 mpg @ 78 mph. So I was happy to say that I was getting such good mileage for a big V8. But it is nice to only be humming along at 1700 rpm's or at cruising speed.

[WARLOCK]

When new I avg 17mpg per tank, 24mpg interstate running.. Which is 85% of my driving. With 28,000 miles
On it now I avg 19mpg to most tanks and I get around 27mpg interstate now. This is with DOD OFF and mods listed below. I usually run 76-80 on the istate. Overall really great fir this car I think. My buddies 06 CTSV avg. Is 13mpg per tank. AND I whip his ass every time we line up muahhahaa

[TurboSS]

For those of you that have posted #s. are you going off what the computer is telling you your average is or are you actually calculating it yourself. I know nothing of this car but i know the system in my navigator is way off. it reads 4-6 mpg more than what im actually getting.

i'll tell you my story. i have figured the mpg with the computer AND by math. always use the same pump when i can. my DIC has had a max error or .3mpg(87oct) for an entire tank of gas. my last fill up was perfect...no error. 0.02mpg difference(93oct). when i drive with mpg as my goal on the highway (speed 55mph with cruise on windows cracked) i avg 30mpg to work....wind and temp play a factor of course. those numbers were with a tune with alot of time spent on the DOD (4cyl mode) for mpg. on a stock car i was avg 26-27mpg same road, same time of day same driving style. i think everyone here knows the key to getting good mileage in these cars is to keep it in 4cyl mode as long as poss. i have a scanguage2 dialed in accurately and i see my instant mpg change by 4mpg at 55mph. city driving...all i can say is be really light on the throttle if you want good mpg. my DOD kicks in at 17mpg...so for closely set stop llights i will only get up to 20ish. 20mph 4th gear with DOD is 34mpg for me....coasting is your friend!! btw...if you want to help increase your mileage or quickly cool off a hot motor before a race here's a trick i found....any speed above 60 while coasting (foot off throttle) will turn off ALL the injectors and they wont turn back on until slowing below 59mph. if you dont want to watch your driving style that close BUT you still want good mileage....look at other cars. hope this helps.

[XXFire]

72 mph cruise, my buddy got 26.7 in my GPX rollin to vegas.

[texn884]

I got today from SAn Antonio to Norman Ok was 26.4 MPG running 74 most of the time besides the time I punched it and a fucking 18 wheeler almost smashed me into a guard rail doing about 95. He never looked and the nose was almost scraping the blacktop. Was not fun but master thru it and went on to get lunch. i got gas and I was getting 28.3 until all the want to be drivers stopped to get in line for some one lane driving in Oklahoma where the roads SUCK!!!!

[piecesparts]

You guys must be doing something that I am not doing. I am getting a good 21.5 to 22.0 MPG on the highway while running at 75 MPH. The city driving knocks this down to 19.5 MPG. I have a Vararam, HSRK, MF exhaust with a X-pipe replacing the center muf. We did a tune locally to get the fuel map more aligned and the shift points tighter, but the mileage is still the same. Maybe if I sat this thing down and actually drove at 70 MPH or less.

[WARLOCK]

Pieces, how many miles u got on yours now? Believe me they will get better mpg after some break in I'm at 30,000 now. I don't baby mine and I never drive less
Than 75 on the I-state. What afr after tune? Mine is still a little rich and all this factored I still get 26-27 I-state. Solid 19 town.

[piecesparts]

Pieces, how many miles u got on yours now? Believe me they will get better mpg after some break in I'm at 30,000 now. I don't baby mine and I never drive less
Than 75 on the I-state. What afr after tune? Mine is still a little rich and all this factored I still get 26-27 I-state. Solid 19 town.


I am around 26,000 and it runs great, but the mileage is not what others tout. If I went with the VMS tune, it might gain, but my wife is a bit of a skeptic and the thought of buying a premium grade fuel makes her all grumpy. I have to believe that either I am doing it all wrong, or there is a little fisherman in most of the others....HMMMMM

[xruling]

2009.5 GT: Just ran 300 miles up I-81 (Bristol to I-66) and a few miles on 11W (filled up in Kingsport) and got 26.8MPG on the one tank of 89 octain gas. SC tune, AC on, cruise control set at about 75MPH. Also listened to mostly country music. Using cruise control makes a big difference in so many ways (e.g., less gas and faster trips). Use it and you will be able to easily ID all those that don't because of the way the constantly speed up and slow down (passing you and then getting in your way). God, I would love to have a train horn on I-81. Surface street driving gives me 14-15MPG with spirited, but not wreckless or attention attacting acceleration.

[WARLOCK]

I am around 26,000 and it runs great, but the mileage is not what others tout. If I went with the VMS tune, it might gain, but my wife is a bit of a skeptic and the thought of buying a premium grade fuel makes her all grumpy. I have to believe that either I am doing it all wrong, or there is a little fisherman in most of the others....HMMMMM

well, i can say i have never put anything but 93 in mine since day one, and i have an intense tune..
I cant speak for everyone here I can only tell you my numbers are 100% accurate. I have been checking my car by gauge and by pencil periodically since it had 10 miles on it. the car is always within 1mpg to my pencil cal.
also i do use my cruise on i-stat every trip.

[piecesparts]

I am on board with the higher numbers, but when I run Interstate, they numbers never seem to go higher than 22 MPG. I know that there are times of foot frenzy involved, but that aside, cruise on, speed at 75 to 77, A/C makes very little difference (it seems). I usually don't get more than 100 to 150 miles per trip, so my mies between city driving moments are limited.

[texn884]

I run mostly highway miles and Monday Patrick G. tuned my car and it is giving me a bit more MPG. Wednesday I was running with a hot chick in a GTO up 35 between San Antonio & Austin and we were running about 90-95 for a good 20 miles and my dash said I was getting 23.3 mpg and then I slowed down to 74 on crusie to Waco and I got 26.1 mpg.
I am going to El Paso Sunday and will set her at about 74 and will see what it does. It is a good 550 miles from my house to the hotel in El Paso so I should get a good 26.5 or better and I will post when I get there. I may try and do a fast run and see what she will top out at on a nice streatch of high wayyyyyyyyyyyyyyy.

My car just turned 19,159 miles since the start of April when I brought it home with 2,800 miles on it.

[GT-610]

I averaged 1.5 mpg higher since the 93 tune if that helps...

[jonnynadeau]

:snow:Here in ND I've gone 85-90 for about 220 miles and got 27.6 mpg (calculated)/27.3 mpg (computer).

[texn884]

HI Johnny sounds like you found the sweet spot with your engine.

What better that hige mileage with a 6.0 engine. Screw the little 4 & 6 cyl. imports or Jap/American made. Love the big V-8 POWER. :)

[Posidon42]

I actually think I get pretty good mileage. With mostly commute traffic (max 2 miles each way) :D and maybe a 20 mile highway run while doing errands every once in a while, I get about 17-18 mpg. The last couple times we took long road trips, I averaged about 25. Both were manual calculations not relying on the DIC to tell me.

[texn884]

I just got to El Paso from San Antonio and the first tank I got 23 mpg that includes two wide open runs at 145mph and the second at 150 mph.
The second tank when I pulled in to El Paso it was reading 29 MPG running 75 in 104 degree temps.