Schantin

iTrader: (6)

I've been thinking of trading my 06 Maxima on one too BTW, you have an auto in the Nissan? I drive my M6 one pretty aggressively and put down 20 around town and 26 on the highway. Bone stock too........

jlrz28

iTrader: (7)

What gears do these cars have? Is it the normal 3.08,3.23,3.42(m6)?

20SS07

You could be a lucky exception then. Most people I know report it's not completely accurate and the DIC in my Impala SS comes up anywhere from almost spot on to up to 2mpg too high.

slick1851

Kind of sad they do this bad, I was expecting more

Bad Habit Bird

iTrader: (12)

Interesting.

I thought it was pretty good for a 4,000lb four door car with a big V8 engine.

How does it compare to the chargers?

BanditTA

iTrader: (3)

There are way to many variables is manually calculating you mpg. Pump stops, fuel tank breathers, tank design etc., if anything the DIC is much more acurate than anything a human could "easily" calculate.

The gears i think are 2.92's, talk about killing gas mileage and performance. Gears that low will lug the **** out of the engine and make gas mileage worse than good, what the hell is wrong with GM sometimes.

Bad Habit Bird

iTrader: (12)

The gears in the rear end are so tall due to the aggressive gearing in the transmission.

malofquist

i feel like a broken record, but my audi rs6 (540hp twin turbo V8) >4200lbs, i would hover on 28mpg on a long mutli hour stretch of hwy.

racerns

Have you taken your G8 on the same long multi hour stretch of hwy? The RS6 is a 4.2L engine which should do better on a hwy cruise if you are not into the boost. Just so you know, by the new 2008 EPA fuel economy rating the G8 GT and a 2004 Audi RS6 have the same city rating at 15 MPG and the G8 is rated 2 mpg better than the RS6 at 24 mpg on hwy. As for the AFM (DOD) response on the hwy I am not sure what you are talking about, it jumps out of 4 cyl mode the instant you tap the gas. Have you watched it on engineer mode? If anything I think GM has it disengaging a little too soon. A few people have seen improved mileage when upping the AFM deactivation point from the 6% throttle positon it is set at to something like 11%.

As a data point I have had my G8 for 2 weeks and only driven 560 miles. On my 2nd tanks of gas (about 1/4 left) I am averaging 18.9 mpg for my drive which is about 2/3 city/back road (lots of stops and starts) and 1/3 hwy (about 6 mile shot each way).

Bad Habit Bird

iTrader: (12)

good post racerns, I plan on adjusting the AFM settings on my G8 as well to see if I can get any more increases in fuel economy

ludicrist2500hd

I went from 24 hwy to 28 hwy by doing this .

caretaker

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.

Semper91-RS

So will swapping in a set of 3.31's make gas mileage improve? The only issue with this that I see, however, is the tranny's individual computer.

GETGONE

iTrader: (5)

Why would putting a higher gear ratio make the mileage improve??? You'd want a LOWER gear to get better gas mileage so the engine is turning lower RPM's. It cruises at about 1500 on the highway as it is in 6th gear.

EnfuegoZ28

25 mpg isnt bad for a 4,000+lbs 360hp car. I wonder if the T6060 will help any with mileage.

jerrad

iTrader: (5)

My caddy gets 25-27 on the highway so with the GXP you should probably expect similar numbers.

GETGONE

iTrader: (5)

I REALLY doubt it considering the GXP may be slapped with a Gas Guzzler tax.

jerrad

iTrader: (5)

Well, the V would have but it had the stupid CAGS installed. the ls3 and ls6 have similar hp rating, car weighs roughly the same, and they will both come in 6 speed manuals.

99-LS1-SS

I believe you could floor a G8 everywhere you go and still get better gas mileage than my Tahoe. 12.8 mpg is painful.

GETGONE

iTrader: (5)

I think my wife does and still gets 16-18mpg!!!