Start saving up for gas haha
just kidding

 

23mpg sounds a little low. Yeah, start saving for gas.

I get around 26-27mpg on the Interstate in my M6 GTO. I would think that the MPG would increase on a car with a better gearing, decent final drive ratios in the A6 and active Fuel Management.

 

Don't forget the numbers are the new EPA testing, so they may be a bit low. Our other car gets much higher than the rated 20mpg highway (we consistently get 25 to 26mpg highway at a good clip) and that is under the old system, but City was always under what the old system rated.

 

Well the Goat M6 gets 15/23 via the 08 EPA ratings. This sounds about right honestly, considering the GTO's M6 should cruise at a lower RPM (right?) with a lighter car, albeit with a more gas hungry motor.

Sounds right to me. And I get a max of 22-23mpg on the highway with Goat, cruising at ~80mph.

 

It's not low, as someone already pointed out this car and all 2008 vehicles are tested with the EPA's new method. It's also about the same as other V8 cars of it's size at different prices.

G8s are not a car you buy for fuel consumption.

 

Stop posting Higher mileages

I get this same thing with people who have BMW 5 series of Chevrolet Corvettes, people saying their V8 cars are getting mid 20s in highway mileage. I've driven many, many V8 cars before, and none of them achieve mid twenties unless you drive like a grandma (a grandma's grandma at that).

When lighter, V6 powered cars are getting low thirties, I dont think we need to be lying about this guys, ok? My parents, in their old age, are trying to be "hip" (their word, not mine) and search car forums for info on real gas mileage and what not, and my dad actually bought an Impala SS (the FWD version we have in the US) because people were saying that they got mid twenties highway mileage. It still beat his old truck, but he is getting 22 or so on the highway, and is pissed at me for ever introducing him to these internets. Lets stop the :gr_devil: speak, ok?

 

Ymmv

I get this same thing with people who have BMW 5 series of Chevrolet Corvettes, people saying their V8 cars are getting mid 20s in highway mileage. I've driven many, many V8 cars before, and none of them achieve mid twenties unless you drive like a grandma (a grandma's grandma at that).

When lighter, V6 powered cars are getting low thirties, I dont think we need to be lying about this guys, ok? My parents, in their old age, are trying to be "hip" (their word, not mine) and search car forums for info on real gas mileage and what not, and my dad actually bought an Impala SS (the FWD version we have in the US) because people were saying that they got mid twenties highway mileage. It still beat his old truck, but he is getting 22 or so on the highway, and is pissed at me for ever introducing him to these internets. Lets stop the :gr_devil: speak, ok?

I now have over 16,000 miles on my V8 – a 2007 Corvette w/A6 trans.
It is my only car & I use mine as a Daily Driver, commuter, etc.
Driven each work day ( perhaps 75% of my driving ) in & out of MidTown Atlanta, my driving typically includes some 70 to 80 mph cruising on the way in, at 6AM, and a 20+ minute ‘slog’ in very slow, bumper-to-bumper traffic moving at 0 to 15 MPH each afternoon.

My overall fuel mileage ( Excel = almost identical to DIC ) currently stands at 22.38 MPG.

I use the full 400 lb/ft of torque most every time I drive. Though typically not for more than short bursts – as I have no interest in annoying the LEOs.

In typical Interstate Highway style driving, I see 28 to 30 MPG in the ‘Vette, setting the cruise control at 75 to 80 MPH. I have recorded 3 full tanks ( primarily highway, with some light back road driving thrown in ) at over 28 MPG – one, with my Daughter & a long weekend worth of luggage calculated 29.04 MPG = 467 miles & 16.08 gallons.

Previous 8 cylinder Sport Sedans I have purchased were typically capable of 25+, when cruising at or below the posted speed limits.

I actually had a 2005 Grand Prix GXP ( Pontiac version of the Impala SS you mention ) and drove that car in essentially the same way I drive the Corvette. Even with DoD I would typically see 23 to 24 in the same highway mode where I see 28 to 30 in the Corvette. The Corvette is ( clearly ) lower & has less frontal area – and it is more aerodynamic - an issue at 75+ MPH. It also is geared to turn that 6.0L V8 slower \ at lower RPM than the 5.3L in the SS & GXP at the same speeds. As I posted elsewhere, my experience was that if you kept the 5.3L V8 cars running below about 65 MPH, they did return decent mileage = roughly the EPA Hwy rating of 27. At 75 to 80 MPH, where I find myself settling in on a long run outside urban areas ( speed limits 65 to 70 ), I’d see that 23 MPG to maybe 24 in the GXP.

And I have never posted anything but what I observe & calculate.

In fact, here is a very old GXP MPG Internet post of mine:

http://townhall-talk.edmunds.com/We...dmunds.com/WebX?14@@.f0e0678/700!keywords=allin:msgtext limit:.f0e0678 rayainsw

- Ray
Just one ‘data point’.. .. ..

 

I'm slightly surprised by these numbers. I mean, yes, it's a performance car. I just hoped the AFM and tuning it would balance out with the new EPA method and the resulting numbers would be like the GTO M6 numbers. So something like 17/25. I guess 15/23 is close. Just somehow the highway number going below 25 feels significant in my mind.

At this point I really want to know what the heck Pontiac plans to do with the manual. Is it coming? Ever? If so, when? And when it does, are the MPG numbers going to get better, worse, or stay the same. I will be driving this thing to work every day, and usually there's enough traffic that I can't drive like a bat out of hell. Work commute will be "grannie" driving. So I'm curious to know whether the A6 or M6 will result in better MPG in real life.

 

Amen Ray - fact of the matter is good gas mileage + big, powerful V8 is possible with the right gear ratios AND a light car. Vettes weigh 3100-3200 lb. The Goat is 3725 and the G8 is near 4000. That is a HUGE difference.

I'm thinking of trading to a used C6 down the road, this 17 MPG lifetime after is terrible!

uvaeeman - the GTO was rated 17/25 in the pre-08 ratings. The 08 EPA ratings put the GTO M6 at 13/22 or something like that, which frankly is pretty accurate.

 

Damn, I didn't know it got spanked so bad with the new ratings. That makes the 15/23 seem better by comparison.

 

How could a car with better engine management, more MPG friendly rear gearing and a 6 speed auto get worse mileage? I'm talking about actual mileage. Not a number someone pulls out of their butt. Are they pulling a boat or going up a mountain? Those numbers sound so screwed. I averaged 27mpg highway with my V8 92 Camaro.

I have every receipt for fuel since the car was new. 16 mpg city and 26+ going 75MPH on the interstate is what my car gets. I bet I could pick up 1-2 mpg with a tune.

 

Automatic = more drivetrain loss - fact of the matter is, a 6-speed auto does more for closer gear ratios than it does cruising RPM.

Your 92 Camaro weighed ~3200 lb - I know, we have one. You simply can't fight weight - this thing is friggin' two tons!!

 

This would be welcomed over my Trailblazer SS, rated 12city/16highway. Thanks in large part due to a 6sp vs. my 4sp trans, as well as a lower final drive ratio (why they put a 4.10 rear end in this truck is a bit beyond me), combined with the lower weight and Cd, as others have posted, seeing 25+ on a highway trip is likely very feasible

 

Some guys here in OZ have hit 8-9 Litres per 100km on the highway... (6.0L)

This is with the non DOD engines.

Say roughly 28mpg i think?

 

converted...



9 would be just over 26 MPG
8 would be 29.4 -
and I'd be impressed with THAT !!!

 

Here is the official numbers.

http://www.fueleconomy.gov/feg/compx2008f.jsp?year=2008&make=Pontiac&model=G8&hiddenField=Findacar

 

24???

So 15 \ 24
Hmmm - not bad, actually ( IMHO )
Though I notice:
Premium Gasoline
Top center.....?????

 

a few additional thoughts...

Here is the context I see for these ( now ‘official’ ) EPA numbers:

G8 A6 = 15 \ 24 [ 2008 ]

Corvette A6 = 15 \ 25 [ 2008 ]
Corvette A6 [ 2007 ] WAS 17 \ 27
Would have been 15 \ 25 under the new \ 2008 EPA scheme

So.

I happened to fill my Corvette ( 2007 with essentially the same A6 trans. as the G8 GT \ V8 will have ) with gas on Wednesday morning & drove from where I live, northeast of Atlanta, to Macon & back. As I was approaching Atlanta on the return leg – after approx. 185 miles, the Driver Information Center AVG MPG read just over 31. This was driving ‘with traffic’ – mostly 65 to 75 MPH on the highway portions, with 10 or 15 miles of in-town traffic driving thrown in. Looking at the both the run down & back cancels out any effect of elevation change.

Thus, if the EPA highway rating for the G8 is accurate, I could expect roughly 30 MPG, in an identical run.

That’d be OK with me . . .

- Ray
We’ll see what owners report in the real world . . .

 

Here is the context I see for these ( now ‘official’ ) EPA numbers:

Thus, if the EPA highway rating for the G8 is accurate, I could expect roughly 30 MPG, in an identical run.

That’d be OK with me . . .

- Ray
We’ll see what owners report in the real world . . .

It's getting deep in here. No way the G8 will ever get close to 30MPG. It weighs about 750 pounds more and is less aerodynamic than the beloved Corvette.

 

Plus these numbers are on 87 octane which saves you what $.25 to $.30 per gallon. That figures to about 25-26 mpg if you were paying for premium fuel.

That make any sense?

 

It actually says 'Premium Gasoline" here:

http://www.fueleconomy.gov/feg/compx2008f.jsp?year=2008&make=Pontiac&model=G8&hiddenField=Findacar

 

That may be a little high. running 87 in a premium recommended car will hit you for about 3% lower fuel economy. At least thats what it is in the LS2. so 1mpg roughly

 

IMO - the EPA highway number wasn't broke, if anything it was on the low side, in our last 4 cars, they all consistently got better gas millage (3-5mpg more) than the EPA rating, all highway driving was in congested areas, and with lots of hills (when driving on LI with no traffic, as rare as that is, I would get even better due to the flat terrain).

I am no light foot, if anything, I like quick brisk acceleration and quick passes, I am definitely not the one to feather the gas.

I would think we could easily get over 27mpg on the G8 based on 24 EPA (especially now that it is lower).

But - only time will tell, and this is all conjecture now!

 

This has been my experience also.

 

Even though its an aging thread....I still will comment..

Getting over the rated MPG means that you would have to drive exclusively on the highway. Mixed driving will never compute to 27MPG for the G8, just as it does not compute to 32 for my G6 thats rated at 29.

If you drive exclusively on the highway from fill up to fill up, meaning you fill up at a highway side station (on some highways at a rest-stop; on the I-81 through VA to NY for example) then you might see some impressive numbers. But don't count on it. I barely got to 32 in my G6, and I had to drive VERY conservatively. Limited my speed to 70MPH, didn't rush to pass, never put the pedal down hard.

And I calculated based on actual callons and distance travelled; the DIC figure said I was getting 40MPG when all was said and done. 8MPG off.... Imagine, that after 400 gallons of burning pleasure, at 40MPG my calculation would be WAY off. The odometer tells the truth. The DIC...in most circumstances...lies.

 

The DIC...in most circumstances...lies.

Hence it's name, DIC.

 

You think your that important that I was commenting solely on your comment?

All jokes aside, I was simply leveling my opinion that 27MPG wouldn't be so "easily" achieved as Mr. need4spd said. What I call mixed driving is not statistical 50/50. It can be 90/10, 80/20, 20/80, 10/100 (Hwy/city)... And besides, the G6 4 Speed is rated according to what the 4 Speed can accomplish. But strangely enough, its rated better than the 08 with a 6 Speed...

I drove a Grand Prix that was rated to 30, and never exceeded that 30MPG by more than 1-2MPG as hard as I tried. The DIC in that car happened to be a bit more accurate, though losing accuracy as MPG went up, but only slightly.

Add a V8 into the question and already MPG suffers. A good 6 speed helps, but when you've got over 700 pounds more "fat" than the Corvette, its going to show. This ain't a corvette. Sure, maybe some people will get close to 27MPG, but the word "easy" signifies that it would be capable of considerably more.

When I look at all the statistics, and how little pedal work it takes to subtract the MPGs at the top end of the scale, I believe that the 24MPG would be closer to the truth. I only achieved near 32 once. But in the same exact conditions, all it took was 10 miles to subtract 4.5MPG from that figure.

I am approaching it from a realistic driving standpoint; in which people are not going to be very often able to drive exclusively on the highways. However, in exclusive highway ideal conditions, 27MPG should be achievable or at least approachable. But I wouldn't bet my next paycheck on it.

And make no mistake, I would surely LOVE to be wrong.

 

important??? me??

"You think your that important that I was commenting solely on your comment? "

Hardly....
More later.
- Ray

 

Well I was just joking , but I thought I deleted that

That seems to be happening to me alot lately...

 

DIC for president!

 

I'm hoping the optimists are right. I'm no pessimist, I tend to hang around the center towards the "realist" sector.

But sometimes, I am surprised.... But I still don't think many people are gonna see a lot higher than 24. Lets face it, how much exclusive highway driving does anybody do?

 

Most of my driving is interstate. I work from home when I'm not on the road. My office is 150 miles one way.
I'd say I'm 85 percent hiway.
At home I can use the wifes Escape for around town.

 

That 15% will be enough to hurt your gas milage considerably. Just 10 miles city vs 250 hwy, and mine lost 4 MPG to 28, where it hit 32 in that same distance, where as with 249.8 Miles Hw2, .2 miles "on/off ramp" I scored near 32.

I stand behind my predictions.

 

I'm not going to argue your prediction. I'm not buying it for the fuel mileage. I just spend most of my time on the interstates.
At least thats the question I thought I was answering.

 

Well I don't want to argue... debating is more like it

Debates don't always have to be inflammatory pain hehehe...