Fuel Economy

[EngineDweller]

Quick question...gotta drive the G8 to Michigan this week, any tips on fuel economy? How well does the AFM work? I dont wanna bring it, but our other car is a lease and already is too close to the mileage than I want it, so the G8 gets a road trip.

[TooManyHobbies]

If you want to get any advantage out of the AFM you cannot exceed the speed limit, have a headwind, or go uphill.

[Doug Hilliard]

My AFM works up to around 75-78 if the road is flat; the lower the speed, the more it will stay on.

[Chewy]

Yeah, my AFM worked well at 73 MPH which is usually where I lock the cruise at. Sure, inclines would switch it off, but it took one HELL of a headwind to do it. I live in the plains and while not the flatest part of the plains, there aren't any mountain grades.


OP, make sure tire pressure is up to par and your air filter is clean and that's about all you can do short of tuning it for better MPG.

Chris

[-Ray-]

LOL
Don't ask cammed and supercharged guys questions about fuel economy. They have no clue. LOL

Start the car in engineering mode. Hold down left scroll wheel and start. Use the scroll wheel to find all active. When engine is in AFM it will change to half active. This is very helpful if you have stock exhaust. After market you can hear the tone change when it goes into AFM.
After 10 minutes in AFM it will kick out for 1 minute. You can defeat this. Kick it out before the 10 minutes and the timer will start again. It takes effort, but you need to feel the throttle to keep it in AFM. Cruise control hurts for the most part. Slight incline cruise will kick you out, but if you can feel the throttle you can stay in AFM.
Down hill you can keep AFM active to almost 80. Use that to have some speed going up any hills. Slowly back off the gas as you go uphill.

[tchr49]

Fuel economy??
I thought that was how much the bastards jack it up from one week to the next.

[EngineDweller]

Hahaha guys Im right there with you...this car was not bought with the intention of saving gas. I just dont have a choice, family emergency and my gas mileage car is a lease. Eventually ill be modding it! Thanks for the input though, it is greatly appreciated

[Frostopsy]

My H/C/I LS3 can get between 25-30 highway. The secret is to find the car's power band and put it in cruise control. Usually it's around 70 mph. Cruise control is the key though. Our only problem is the small gas tank.


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[LDM]

Don't ask cammed and supercharged guys questions about fuel economy. They have no clue. LOL


I got 24.4 MPG on the trip to and from the dyno in CT. That included the dyno pull.

[HVYCHVY]

I was getting about 26 running 85 according to the DIC. You can air up the tires to 50 psi and get less rolling resistance.

[-Ray-]

I got 24.4 MPG on the trip to and from the dyno in CT. That included the dyno pull.

I was getting 29 and once got 30 mpg when I had AFM.

[EngineDweller]

Ill be leaving around 1 eastern time, ill post my mpg for the first leg and let you guys know. Ive been running premium fuel, you think I should run 85 or 87 instead?

[Chewy]

If it's not tuned for premium, run mid grade. 89 I believe is what it calls for.

[EngineDweller]

All the owners manual says is at least 87, but the midgrade will save me 10 to 20 cents a gallon. Thanks!

[-Ray-]

Unless you have a custom tune run 87 octane.

[Bob the Noob]

Don't ask cammed and supercharged guys questions about fuel economy. They have no clue. LOL

What's next Ray, a jab at V6 owners? ;)

On a trip from Michigan to Maine I got around 25-26mpg... There's some very low frequency drone with my exhaust so it was easy to know when AFM was on which worked in my favor.

[Bob the Noob]

Quick question...gotta drive the G8 to Michigan this week, any tips on fuel economy?

Where abouts in Michigan you going? I'm sure some of us could advise good spots to eat or things to see if you have time. Also, check out gasbuddy's app if you have a smartphone. Gas can vary by 10-15cents a gallon, sometimes more, within a few miles.

[Slizzo]

My H/C/I LS3 can get between 25-30 highway. The secret is to find the car's power band and put it in cruise control. Usually it's around 70 mph. Cruise control is the key though. Our only problem is the small gas tank.


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I wouldn't necessarily call 19gal small...

[Frostopsy]

I wouldn't necessarily call 19gal small...

For a 4000lb car with a 6.0L V8? Yah, pretty small. You only have 16 gallons before the gas light comes on. The TBSS has a 22 gal tank.


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[Bob the Noob]

(shrug) our 'Burb has a 30something gallon... it's all in how you drive it.

[EngineDweller]

300 miles, 3/4 tank, 5 hrs @ 64 mph avg.

[-Ray-]

What's the mileage?

[EngineDweller]

All the way through. I made it at about 24-26 mpg for the whole trip, and that was cruising between 72-78. Very impressed honestly. Now when I get back to NJ my tranny pan will be in lol. I am Not counting the last 45 minutes, someone thought their car was tougher than a guardrail...flipped their car onto its side.

[EngineDweller]

What's the mileage?

First half was 24.6 mpg on the dic. Gotta pull the receipt and do math in the morning. To tired right now haha.

[EngineDweller]

Where abouts in Michigan you going? I'm sure some of us could advise good spots to eat or things to see if you have time. Also, check out gasbuddy's app if you have a smartphone. Gas can vary by 10-15cents a gallon, sometimes more, within a few miles.

In Chesterfield. My wife is actually from here, but im all ears when it comes to food!

[Slizzo]

For a 4000lb car with a 6.0L V8? Yah, pretty small. You only have 16 gallons before the gas light comes on. The TBSS has a 22 gal tank.


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What about a 4400LBS with a supercharged 6.2L V8? Because the CTS-V has a smaller tank than we do...

[Bob the Noob]

In Chesterfield. My wife is actually from here, but im all ears when it comes to food!

Bad Brad's BBQ might be an option, I've heard it's good. If you're around 696/94 area (highways) There's a place called Lazybone's Smokehouse which is awesome. I don't know of many places aside from Brad's that's up that way though.

If you get down to the St. Clair Shores area there's a lot of good places, New York Deli at 10mile and Little Mack... REALLY good Ruebens.

Check out yelp.com for some local places, I'm sure you'll find some good stuff.

[EngineDweller]

Bad Brad's BBQ might be an option, I've heard it's good. If you're around 696/94 area (highways) There's a place called Lazybone's Smokehouse which is awesome. I don't know of many places aside from Brad's that's up that way though.

If you get down to the St. Clair Shores area there's a lot of good places, New York Deli at 10mile and Little Mack... REALLY good Ruebens.

Check out yelp.com for some local places, I'm sure you'll find some good stuff.

You had me at Ruebens haha. Definitely have to check that out so thanks!

[Bob the Noob]

They have a triple decker, corned beef/pastrami but you can get it grilled with 'kraut. The 'strami is sometimes fatty though, good flavor but not everyone likes it that way.

[turbo2nr]

i think something is up with my g8, i've been getting 18-20 hi way and 10-12 local.

And i havent been abusing the car too much.

[EngineDweller]

i think something is up with my g8, i've been getting 18-20 hi way and 10-12 local.

And i havent been abusing the car too much.

Whens the last time you did an oil change? Could have an affect. Also, dont always trust the dic, could be off. Also, what is your highway speed and distances? Cuz in NJ I only get about 18-21on the highway back and forth to work. And my city is probably arpund 12-14.

[texn884]

The best I've got was 30 mpg. I'm kinda the king of mpg. I'm taking the Black Rat out to El Paso and New Mexico starting Sundays and will put on a good 2000 miles. I hope it does good since the new engine is pretty much broken in now.

[turbo2nr]

I am getting about 12-14 city as well.

I guess i do more city then highway. I am due for a oil change withing the next 700miles. I will also change my spark plugs for the hell of it. Put some ngk's in.

[EngineDweller]

I think it really depends on the city lol. In nj I get the 12-14, but here in mi I'm getting about 16. Not as many stoplights I think is what it is.

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[piecesparts]

On a trip from Lebo, Kansas to Atlanta, Georgia, I averaged around 23 to 23.5 MPG with an average speed of 78 MPH. There was one tank full that I ran along at 65 MPH, on a two-lane highway across Kansas and did a good solid 25.5 MPG. I have no headers,, but I do have a Vararam CAI, a HSRK, an EFI Live tune, Magnaflow catbacks, and a 'X'-pipe where the front resonator used to be. I keep my tires at about 36 PSI and I use my cruise a lot. I run along with traffic, which is usually just above the set speed limit, thus the 78 MPH.


Grass has never been known to grow under me!

[EngineDweller]

On a trip from Lebo, Kansas to Atlanta, Georgia, I averaged around 23 to 23.5 MPG with an average speed of 78 MPH. There was one tank full that I ran along at 65 MPH, on a two-lane highway across Kansas and did a good solid 25.5 MPG. I have no headers,, but I do have a Vararam CAI, a HSRK, an EFI Live tune, Magnaflow catbacks, and a 'X'-pipe where the front resonator used to be. I keep my tires at about 36 PSI and I use my cruise a lot. I run along with traffic, which is usually just above the set speed limit, thus the 78 MPH.


Grass has never been known to grow under me!

My G8 doesnt have any mods yet. Cant wait to start. And how do you like the magnaflow cats? I cant do long tube headers, so the kooks system is outta the question. Gotta start looking into a new plan. And yea, 78 is about my avg highway speed here...although thats 13 over, everyone drives 80 here.

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[piecesparts]

My G8 doesnt have any mods yet. Cant wait to start. And how do you like the magnaflow cats? I cant do long tube headers, so the kooks system is outta the question. Gotta start looking into a new plan. And yea, 78 is about my avg highway speed here...although thats 13 over, everyone drives 80 here.

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Until I put the X-pipe in, there was a lot of drone in the car. The X-pipe moved the sound to the tail end of the car and it is very manageable, now.

[travis gore]

on our trip to Florida last week. 26 avg mpg running 73 mph in no hurry driving down. coming back 22 avg mpg 80-90 mph. AFM is still on mods are ARH no cats stock mufflers Varraram with a Vector tune for 93

[Chewy]

I drove out to my buddies house the other day mostly highway and country roads, and on the highway I was seeing high 19's low 20's, but when I got home I saw 13.1 average and I reset it before going. OUCH! I really want to put the 3.27 back in.

[Featherburner]

My G8 doesnt have any mods yet. Cant wait to start. And how do you like the magnaflow cats? I cant do long tube headers, so the kooks system is outta the question. Gotta start looking into a new plan. And yea, 78 is about my avg highway speed here...although thats 13 over, everyone drives 80 here.

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Why can't you do long tubes?

[EngineDweller]

Why can't you do long tubes?

I was told its illegal in NJ to do long tubes. Something about moving the position of the cat. Havent really dug into it yet, as I dont have the $$ to do exhaust yet. But it was my uncle and he knows the rules better than I do here. My list of reasons to stay in NJ is getting very short haha. I would love to do a full kooks system if allowed this state!

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[Featherburner]

I replied to your pm but long tubes are doable in Jersey. As long as it has cats and no CEL you should be fine.

[-Ray-]

I was told its illegal in NJ to do long tubes. Something about moving the position of the cat. Havent really dug into it yet, as I dont have the $$ to do exhaust yet. But it was my uncle and he knows the rules better than I do here. My list of reasons to stay in NJ is getting very short haha. I would love to do a full kooks system if allowed this state!

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Moving the cat location is a federal law, in addition to some states.

[EngineDweller]

As usual, thanks guys!

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[AVIDMOTION]

I have had headers on my last 4 cars here in Nazis jersey. All had hi-po cats and X pipe. The cats at one point had to have a card showing it was approved. Last 8 years no issue. Needed to have no codes in memory and pass exhaust test. Nj has since dropped visual inspection. You will have no problem with headers and inspection.
Check my SIG for mods. Traveling from nj to Florida with family and full Ac on using vector 93 tune and varying fuel at half tank with 93 then 87....72-78 mph I get 23.7 on way back from Fl to nj I get 22.3.
City 17-19.7 worse 15...

[EngineDweller]

They dropped the visual inspection? When the hell did they do that lol. Where an NJ are you?

[AVIDMOTION]

Last year, just a port plug in to check codes and a tail pipe pollution test. Yipee! I live in cherry hill nj 8 miles east of philadelphia pa.

[EngineDweller]

Oh ok...I live down in Forked River, work on LBI. I got the car inspected right after purchase, but didn't really pay attention to if they used the camera. I've seen quite a few G8s popping up around here lately. There was only 3 in town including mine, I think the count is at 6 now...but most of them don't want to chat lol

[AVIDMOTION]

...base model v6 owners don't seem to want to chat when seen on the road....

[EngineDweller]

Lol well, the only guy that I have talked and met up with is a V6 guy, this gentleman I saw was in a black GT and I tried to talk to him about his car and he wanted nothing to do with it...it is tourist time...but he had NJ tags. Who knows. Maybe cuz I'm younger (I'm 26) he thought I was a douche lol

[1313]

Currently getting 21-22 highway and 10-12 city.

09 G8 GT
VCM Intake
224/228 Cam
Kooks long tubes & x pipe
3.27s
Yank SS 2800

[texn884]

A federal law to move your cats but its totally legal to import millions of illegals and pay for their asses, WTF



Moving the cat location is a federal law, in addition to some states.

[texn884]

The best ive got on the highway was 32 but my last trip to Wisconsin was best was 27-28. For a BIG fast car to me you cant beat it, well you can but just keep the lights down, lol

[piecesparts]

The best ive got on the highway was 32 but my last trip to Wisconsin was best was 27-28. For a BIG fast car to me you cant beat it, well you can but just keep the lights down, lol

32 MPG at what speeds?

[AVIDMOTION]

My cats are in same place as stock. End of exhaust manifolds at collectors, same with my kooks headers, mids...cats then X pipe...

[RxApple]

Best I've gotten was 33 at 80mph, but I don't have proof. Have this though. 557rwhp and stock gears and converter. Not too shabby I'd say. It's still better than my 2.4L AWD Terrain gets at 70mph.
http://tapatalk.imageshack.com/v2/14/08/27/de1897ad613bcfd2dd932d247b991bd9.jpghttp://tapatalk.imageshack.com/v2/14/08/27/3784284a8464c933afd0294e6629bb55.jpghttp://tapatalk.imageshack.com/v2/14/08/27/c8a5a785a8b6a998220fda46fc207631.jpghttp://tapatalk.imageshack.com/v2/14/08/27/7b8085c6f708fa0db07090ffb721b8b6.jpg


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[texn884]

running 75 it was on a trip from Helotes, TX to El Paso and that was with the original engine.

My new engine is just getting broken in now with about 20,000 miles on it so the mpg are going up.

I use the cruise all the time on the open road

[texn884]

heres one pic at 30.5 mpg
http://i871.photobucket.com/albums/ab271/texn884/f8e4ed7c.jpg (http://s871.photobucket.com/user/texn884/media/f8e4ed7c.jpg.html)

[texn884]

about 1200 miles after the new engine was put in.

http://i871.photobucket.com/albums/ab271/texn884/e12bd58d.jpg (http://s871.photobucket.com/user/texn884/media/e12bd58d.jpg.html)