Bought my Liquid Red G8 GT last week and so far I am getting terrible gas milage. 12 miles to the gallon ( I did put in plus gas)I do alot of city driving, but 12 miles?? Also when do you use the sports mode? I did read the book and color me stupid, but I am wondering if you use sports mode only for freeway or city driving too? Will it help or hurt my gas milage in sports mode? I also know you have to brake it in, my baby only has 280 miles on her... Thanks for any tips:).

thats about what i get for city driving. Will real CONSTANT stop and go gas mileage isn't good. On the highway, the highest I saw was 32.3!!!!!!!!!!!!!!!!!!!!!!! I couldn't believe it. I was going at a steady pace of 90 mph for about 10 minutes straight

thats about what i get for city driving. Will real CONSTANT stop and go gas mileage isn't good. On the highway, the highest I saw was 32.3!!!!!!!!!!!!!!!!!!!!!!! I couldn't believe it. I was going at a steady pace of 90 mph for about 10 minutes straight

...straight *cough* downhill *cough*

:D

I'd imagine the OP's 12mpg is mostly the result of a heavier new owner foot combined with typical city driving. If I race around town, I get horrible mileage, but if I cruise on the highway it'll more than double.

I was flogging mine today in the mountains, showing off with my 300# brother in the car and still couldn't get it to go below 15mpg.:dunno: I'm 300# as well so that was 600# of passengers.:eek:

Lowest I've ever seen over an entire tank was 15.2...all bumper-to-bumper morning and afternoon traffic.

I only use the sport mode when I'm planning to blow past someone that's driving slow or merging from a stop into a 55mph highway(more like 70mph).

Sport mode should be a little harder on your fuel mileage. Mainly, it lets your engine rev higher before shifting up. That's usually detrimental to fuel economy.

I put it in regular mode when driving around town or on highway. If I want to have a little fun, manuel mode. But if i were to race someone, sport mode. I do all highway driving. PUT IN 87 OCTANE! If your car is NOT tuned for 93 or 91, why put it in? 87 is what the car is tuned for stock, so just put in 87 lol. You wont get any better mileage with 91 then 87. But its your gas and your money lol. Take some pics of your G8 and post it in the Liquid Red only thread in the lounge. Congrats!!!!!!

I checked mine, 12.6mpg today. I was wearing my lead boots though. If you dip into the throttle at all, the mileage drops like a rock in this car. However if you keep it in D, and keep the shifts no higher than say 2200rpm - it does pretty good. I did that one day and got 20.8mpg on my way to work which is about 7 miles on the freeway and 2 miles in the city.

you bought a v-8 and you still want good gas mileage I must have missed something:laugh: :laugh: this is a performance car not a rice burner

I could swear the manual says "91 octane recommended but can run on 87 octane".

Regardless, I run 92 or 93 octane. In the Midwest (relatively flat terrain), I have acheived 24-25 mpg using normal mode with the cruise set at 74 mph. Average speed for those tanks was close to 72, which meant those were true nearly 100% highway trips except for brief stops to eat, gas up, etc.

This motor has a knock sensor, which I would assume would allow a little more timing even when things heat up if you are running 91-93 octane. The additional timing probably helps the motor make a little more torque and hp - nothing big but let's put it this way, you won't see me hit the drag strip with 87 octane! :)

BTW, in 60/40 hwy/city I'm averaging about 18.5 mpg. And that with a fair amount of quick take-offs from lights (but not WOT) + and playing around a little on the hwy. Overall, I'm pretty impressed.

Must go, must go faster... no choice...

CAI
Tune
Exhaust
Buy stock in Sunoco
Get gas card with rebates

For LS1-based motors, 1800 RPM is the sweet spot, so whatever cruising speed gets you 1800-1900 RPM will give you the best mileage.

After 5000 miles on my car, I found that the best mileage is obtained by trying to keep AFM active. Weather your doing 30 in town, or 70 on the interstates.

I put it in regular mode when driving around town or on highway. If I want to have a little fun, manuel mode. But if i were to race someone, sport mode. I do all highway driving. PUT IN 87 OCTANE! If your car is NOT tuned for 93 or 91, why put it in? 87 is what the car is tuned for stock, so just put in 87 lol. You wont get any better mileage with 91 then 87. But its your gas and your money lol. Take some pics of your G8 and post it in the Liquid Red only thread in the lounge. Congrats!!!!!!

So you say, yet all the test data I come across seems to be using premium.

I get about 12 to 15 in town and with a trip to JBA Headers about 130 mile trip I got 24.5 wish this car had a instant MPG like the GTO does then it would be easy the find the right spot for best MPG.

I get about 12 to 15 in town and with a trip to JBA Headers about 130 mile trip I got 24.5 wish this car had a instant MPG like the GTO does then it would be easy the find the right spot for best MPG.

I thought you could use engineering mode for that?

So you say, yet all the test data I come across seems to be using premium.

Manual clearly states to use 87 octane fuel. :) Pull it out and take a look.

As for testing, well is that Magazine testing? I'm pretty confident that they don't read the owners manuals for the cars they test. :wink2:

Manual clearly states to use 87 octane fuel. :) Pull it out and take a look.

As for testing, well is that Magazine testing? I'm pretty confident that they don't read the owners manuals for the cars they test. :wink2:

You are refering to the same manual that wants me to put the tire chains on the front tires? There's a reliable source. :rolleyes:

You are refering to the same manual that wants me to put the tire chains on the front tires? There's a reliable source. :rolleyes:

By that same logic I guess you're going to put straight 30 weight oil in your G8 because you already have it on hand for your mower and hey, nobody can trust the manual anyways.:rolleyes:

I don't believe those that say the car was tuned for 87 octane, it will run 87 but it will run better on premuim. It would have been a marketing SNFU to make it premium only.

I don't believe those that say the car was tuned for 87 octane, it will run 87 but it will run better on premuim. It would have been a marketing SNFU to make it premium only.

But it will run better on premuim?? I'm sure you have some type of proof to back this claime up?? Perhaps you've proven this claime on the dyno?

I can understand if you want to feel better about payin $0.20/gallon or more for premium fuel and not want to spend the money for a tune, but you're waisting your money.

If you were two drive to identical cars straight off the showroom, with one having 93 and the other having 87 you couldn't tell the difference...

...it will run 87 but it will run better on premuim.

Proof?

I thought you could use engineering mode for that?
You mean there is a mode I have not found guess it's back to reading the manual :slap:

You mean there is a mode I have not found guess it's back to reading the manual :slap:

Hold down the roller on the left side of the steering wheel (enter) while starting the car with the key.

Enjoy.:wink2:

Hold down the roller on the left side of the steering wheel (enter) while starting the car with the key.

Enjoy.:wink2:

Thanks I will try that when I get it back :)

Back to OP...

If you want better mileage, don't put it in sport mode at all.

And baby the throttle.

The Great American Experiment of the Double Nickel was foisted upon us by a bunch of goody two shoes who claim that even that is too fast for best mpg, that optimal mpg is at a steady state 45 mph on forward sloping downhill run w/o curves, basically I80 from Denver to Kansas City.

Which speed is best for the least fuel mileage? Zero. Don't drive the car. Shouldn't have bought it if you were concerned with fuel mileage.

But it will run better on premuim?? I'm sure you have some type of proof to back this claime up?? Perhaps you've proven this claime on the dyno?

I can understand if you want to feel better about payin $0.20/gallon or more for premium fuel and not want to spend the money for a tune, but you're waisting your money.

If you were two drive to identical cars straight off the showroom, with one having 93 and the other having 87 you couldn't tell the difference...

Proof would be, lacking the aforemention back to back dyno runs in Pontiac's high recommendation of premium over regular, even to the points of conducting EPA certification for emissions and mpg on premium. I'm still waiting to find out if the SAE certification of the engine was done (as I suspect) on premium - which would in and of itself mean one thing - that the engine was tuned on premium. Why recommend premium if it were tuned on 87. ANy car tuned on regular will run on any higher octane fuel without any modification whatsoever, however a vehicle tuned for 91/93 requires re-tuning, whether operator accomplished or engine control accomplished to run w/o knock on 87.

Proof would be, lacking the aforemention back to back dyno runs in Pontiac's high recommendation of premium over regular, even to the points of conducting EPA certification for emissions and mpg on premium. I'm still waiting to find out if the SAE certification of the engine was done (as I suspect) on premium - which would in and of itself mean one thing - that the engine was tuned on premium. Why recommend premium if it were tuned on 87. ANy car tuned on regular will run on any higher octane fuel without any modification whatsoever, however a vehicle tuned for 91/93 requires re-tuning, whether operator accomplished or engine control accomplished to run w/o knock on 87.


FWIW, my manual does recommend fuel with a minimum octane rating of 87. Howwever, in the supplemental "quick guide", premium fuel with a minimum octane of 91 is recommended for optimum performance.

Which speed is best for the least fuel mileage? Zero. Don't drive the car. Shouldn't have bought it if you were concerned with fuel mileage.

I love statements like this. Because ppl want to get good gas mileage on the highway or wherever, they shouldnt have bought this car? Did you ever think people just like to be consious and care more about just how fast the car goes? I for one care a lot about my MPG and want to achieve really decent numbers. Does that mean I should buy a Civic? No. I love driving my G8 GT, its a lot of fun. But just because some people care about how good of gas mileage they want or how to achieve the best doesnt mean you gotta rag on them or make obnoxious posts. Worrying about gas prices or MPG doesnt mean you should trade your car in for a Prius.

The car gets what it gets. There is no magic formula or pedal up down press pull combinations of windows up or down and ac on full defrost that is going to make it miraculously get 50 mpg. If fuel mileage is a constant worry, then yes, you bought the wrong car. EPA estimates are just that, estimates. The state on the sticker that real world mileage will vary. Some cars may get better, some may get worse. If you bought the car to drive a 100 mile commute each day and are worried about your mileage, then you should have bought a different vehicle. But not a Prius, their mileage claims are probably the worst in the industry. You can get better from a Honda Fit.

Good God, Sometimes I have to wonder? If I wanted an economy car that's what I would had bought. All I asked is drive vs. sport mode to get more mpg. Also what all was getting mpg. I don't understand why people have to make a mountian out of a molehill. I got a great deal on my Liquid Red GT baby, and I don't have one single regret. A simple question deserves a simple answer. Give me a break! LMAO. By the way, Gas milage is NOT a constant concern.Get real here, i'm not grandma!.. Just a question!!!!

I still disagree. Whats wrong with having a nice, fast car, while still wanting decent mileage? Not looking for 50 mpg, but if you want to worry about your gas mileage, who cares? Why is it such a big deal for ppl to want decent gas mileage and still have a powerful car? I think what gets people is a 1998 WS6 Trans Am weighin in at 3,400lbs with outdated electronics and engine parts is able to achieve better gas mileage. I realize this isnt a super MPG car and im fine with it. But when ppl ask for advice on how to get better mileage or best speed to get great mileage, tellin them "if you worry bout gas you bought wrong car," is just stupid. It's there money. If they wanted to buy a bulldozer and commute to work, there choice. But because they want to know how to get most out of there car they should not be flamed or have stupid statements like "you should have bought different vehicle if your worried bout gas mileage." So if gas went to $10 a gallon, im guessing you would be OK with it and still say "why you worryin bout gas? go buy a fit."

idk, to me getting decent/good gas mileage is important when you travel 70 miles a week. Some ppl who fill up 2 times a month compared to those who fill up 5-6. I knew this car wasnt awesome on MPG. I bought it cause I love driving it, looks mean as hell, nice ride, interior is sweet, and overall, its amazing. But because I worry about MPG or do 65mph on highway to get best gas mileage, doesnt mean I bought the wrong car. I can see if you bought a Ford Excursion and wanted good gas mileage, cause thats not gonna happen lol. But ppl want to enjoy there car and get good gas mileage, go for it. They didnt make the wrong car purchase, they are just trying to get most out of their vehicle.

Nikeair, DITTO!!! I could not had said it any better myself!!! You Rock!!!!

I love statements like this. Because ppl want to get good gas mileage on the highway or wherever, they shouldnt have bought this car? Did you ever think people just like to be consious and care more about just how fast the car goes? I for one care a lot about my MPG and want to achieve really decent numbers. Does that mean I should buy a Civic? No. I love driving my G8 GT, its a lot of fun. But just because some people care about how good of gas mileage they want or how to achieve the best doesnt mean you gotta rag on them or make obnoxious posts. Worrying about gas prices or MPG doesnt mean you should trade your car in for a Prius.

Okay, then I'll answer the question.

As slow as possible, is the best speed to drive for optimal fuel mileage. 45mph on the highway should do it, if you don't get arrested (min speed on highway is state dependant). Drag increases at a non-linear rate as your velocity increases linearly. The slower you go, the better.

The real way to not get crap gas mileage (15mpg) is to keep your foot out of it. Use cruise control on the highway as much as possible, yadda yadda.

I've seen my average fuel economy go up (2300 miles on the odometer now) over the last month. I got 24mpg on the highway this past weekend, averaged 20mpg for the last mixed tank (calculated, not computer guessed).

You're not going to magically get good gas mileage, period. You may save a few mpg, but it is barely worth the effort.

Well to draw a comparison, I averaged single digits the first tank of my goat. It's gotten somewhat better, with an average of about 18 or so. Hope to do as well with the GXP.

After this thread got hijacked the first time I went back to the OP question and answered it. Since no one else had felt the urge to tell the nice lady not to drive in sport mode if you want better mileage. Now since it got jacked again, I guess I will respond to the current conversation as well.

Being conscious of your current mileage is a good thing. I keep tabs on mine every time I fill up. It lets me know how I am driving. If I drive conservatively I get the 20's easily. If I spank her, it drops like a rock. Now what is an irritation to me and I can assume hellfyre feels the same is when you come across someone in something like a Tahoe and they complain because they get 12 mpg. I see this on the news all the time, reporters interviewing people at gas stations saying "The price of gas has caused a hardship on me and my family" and then they are sitting there filling up a Hummer.

I wasn't trying to say don't keep an eye on it, that is way off base. If you drive reasonably, you can get the EPA estimate easily and maybe even better. But if you drive any vehicle aggressively its going to get worse. Before this car I had a Mazda Protege 5 that I drove like a scalded dog and the 2.0 four cylinder in it only got me around 25-27 mpg. But with this car I don't have to gouge it to get where I want like I did that thing.

The G8 is a great car, for an engine this size to get the mileage it does, is pretty incredible in my opinion. But just don't be surprised if when you tell her to go, she wants some go juice in return. :)

Good God, Sometimes I have to wonder? If I wanted an economy car that's what I would had bought. All I asked is drive vs. sport mode to get more mpg. Also what all was getting mpg. I don't understand why people have to make a mountian out of a molehill. I got a great deal on my Liquid Red GT baby, and I don't have one single regret. A simple question deserves a simple answer. Give me a break! LMAO. By the way, Gas milage is NOT a constant concern.Get real here, i'm not grandma!.. Just a question!!!!

I don't drive in traffic that much. Usually all interstate miles, and some through the county roads in my county. My best mileage was 26.1 in combined in town and interstate driving. If I fill up and reset the DIC and drive around town, 14 to 16 is the best I get.
Sport mode is for more aggressive driving. It will hold it in gear even if you let off the gas. That's so you can corner and the car won't upshift on you. I've left it in sport mode getting on the interstate, and it took quite a bit to coax it into 6th gear.
My feeling is you don't yet have the feel for AFM. Outside of WOT, and hi speeds, I think this is the single most important factor in increasing your mileage.
Get your car up to 30 to 40 and try and feather the gas pedal. You should feel a slight vibration as it goes into AFM. Otherwise, press the left roller on the steering wheel as you start your car. Scroll down using the same roller to find the AFM. You'll see it change to half active. Once you understand and can feel AFM kick in, you'll see your mileage go up.

After this thread got hijacked the first time I went back to the OP question and answered it. Since no one else had felt the urge to tell the nice lady not to drive in sport mode if you want better mileage. Now since it got jacked again, I guess I will respond to the current conversation as well.

Err...check post #4.:wink2:

:bootyshake::p

I've never gotten any higher than 17 or 18 mpg. But, then again - I drive around like I'm freakin' hot SH*T. :)

I drive around like I'm freakin' hot SH*T. :)

In other words, stay outa your way? Is this a postpartum thing, or have you always been this way?:err: