ousig2408

Sabr I am surprised the 6 speed is not returning better mileage than that (well I am not very surprised). we get as good or better mileage with the "old" 4 speed...I know there is a lot more involved with mileage than just adding 2 more gears but I would also think it would = some better mileage

SabrToothSqrl

the 6 also add a lot of smoothness to the vehicle, and it's the same tranny as behind the 6.2L so it can take a lot of power no problem...

Towing with it is so nice as well, uphill in 4th, with 2 more gears on top of that!

it just glides along..

The MPG isn't huge, but neither is the return from shutting off the alternator, but each bit does help...

I also drive it a bit 'fast' I cruise at 72-75, often 80 mph between Harrisburg and York...

73shark

My 2010 is about 10% better than the 2007.

vrso2

i getting about 13-14 town and up to 16 hwy (i'm just finish 450 miles trip-full loaded with stuff, i got 305x40 R22 wheels and i was speeding up to 75 mph.)

in2pro

I have found that speed can be the real killer on MPG, when we were driving around in Yellowstone back in June most of the time our speed was 45mph or less and even with the mountainous/hilly terrain I got 18mpg... seems like once you break the 50-55mph the mpg just doesn't get much better...I guess its a lot of truck to push thru the air....

SabrToothSqrl

I read long ago the 'best' mpg mph is about 45 depending on the exact vehicle.

Drag is exponential... the faster you go, the more gas it takes!

ousig2408

with ours it seems that 60 - 65 is the sweet spot on the highway. 70+ drops mpg quickly. there is no way I would drive slower than that on the highway...driving at 70mph almost gets you run over 1/2 the time.
I try to stay 65 - 70 and I can milk out 20mpg pretty easy on a 100+ mile trip.

in2pro

MPG ratings are a calculated average, not a minimal guaranty, hence the "estimated" city and highway....you should get somewhere in that range a plus or minus range.

Wikipedia has enough info on it to make your head spin
http://en.wikipedia.org/wiki/Miles_per_gallon

Here is a bit of the article and how it is calculated

EPA testing procedure through 2007
Two separate fuel economy tests simulate city driving and highway driving: the city driving program consists of starting with a cold engine and making 23 stops over a period of 31 minutes for an average speed of 20 mph (32 km/h) and with a top speed of 56 mph (90 km/h); the highway program uses a warmed-up engine and makes no stops, averaging 48 mph (77 km/h) with a top speed of 60 mph (97 km/h) over a 10 mile (16 km) distance. The measurements are then adjusted downward by 10% (city) and 22% (highway) to more accurately reflect real-world results. A weight average of city (55%) and highway (45%) fuel economies is used to determine the tax.[31]
In some cases, this tax may only apply to certain variants of a given model; for example, the 2004–2006 Pontiac GTO did incur the tax when ordered with the four-speed automatic transmission, but did not incur the tax when ordered with the six-speed manual transmission.
Because EPA figures had almost always indicated better efficiency than real-world fuel-efficiency, the EPA has modified the method starting with 2008. Updated estimates are available for vehicles back to the 1985 model year.[32]

EPA testing procedure: 2008 and beyond
New fuel economy label.
As a means of reflecting real world fuel economy more accurately, the EPA adds three new tests[33] that will combine with the current city and highway cycles to determine fuel economy of new vehicles, beginning with the 2008 model year. A high speed/quick acceleration loops lasts 10 minutes, covers 8 miles (13 km), averages 48 mph (77 km/h) and reaches a top speed of 80 mph (130 km/h). Four stops are included, and brisk acceleration maximizes at a rate of 8.46 mph (13.62 km/h) per second. The engine begins warm and air conditioning is not used. Ambient temperature varies between 68 °F (20 °C) to 86 °F (30 °C).
The air conditioning test raises ambient temperatures to 95 °F (35 °C), and the vehicle's climate control system is put to use. Lasting 9.9 minutes, the 3.6-mile (5.8 km) loop averages 22 mph (35 km/h) and maximizes at a rate of 54.8 mph (88.2 km/h). Five stops are included, idling occurs 19 percent of the time and acceleration of 5.1 mph/sec is achieved. Engine temperatures begin warm. Lastly, a cold temperature cycle uses the same parameters as the current city loop, except that ambient temperature is set to 20 °F (−7 °C).
EPA tests for fuel economy do not include electrical load tests beyond climate control which may account for some of the discrepancy between EPA and real world fuel-efficiency. A 200 W electrical load can produce a 0.4 km/L reduction in efficiency on the FTP 75 cycle test.[34]
Following the efficiency claims made for vehicles such as Chevrolet Volt and Nissan Leaf, the National Renewable Energy Laboratory recommended to use EPA's new vehicle fuel efficiency formula that gives different values depending on fuel used. Meanwhile an Israeli firm last urged the EPA to come up with a three-pronged number that would tell people how much electricity a car uses when it's fully charged, how much electricity it takes to charge the car and how much gas the car uses when it's out of juice.[35]

RedOctober

ummmmm not sure if all of u have figured this out yet or not... they lie

i might average 22mpg if i drove downhill all day every day without ever stopping.. ever...

otherwise, you'll get what we all get with an 07 LTZ. about 12-14.
enjoy.

in2pro

I've been tracking my overall tank MPG for the last 3 years ( thou I lost some data points due a disk drive crash doh!)
out of 133 data points (fill ups) I average 17.1 MPG overall

with the 5.3 2wd w/3.42 gears, this includes some towing of a 2k lbs camper trailer.

I run 87 octane adding 1 bottle of Techron about every 7-10 fillups, I use top tier (Shell & Chevron) most of the time and Exxon.

I will be rolling over 50k sometime next week, its an 07 3yrs old this month...