OK so I thought I would post my impressions of the new (09 sierra crewcab 4x4) truck. I just finished a 3300 klm (1900 mile) 32 hour trip from Alberta Canada to south western Ontario Canada and the truck performed flawlessly with the exception of everytime I stopped to put gas in it (5.3 litre) the truck didnt want to start to well it would crank and crank and crank and then would start I went to the GM dealer today and they say they havent heard of any other reports of a similar problem. Anyone else heard of an issue like this? OH YA and there is the little issue of it being hard on gas (only have 6500 klms on it) and I hear that should get better but it is definately harder on gas than my old truck (2000 silverado 5.3) Other than those 2 little issues Im lovin the truck it is definatly great to drive comfortable and handles snowy roads like a champ. I have to say all in all it has to be the best truck on the market Ya I know Im a chevy guy and wouldnt even think of any other brand truck LOL

 

The reason it gets worse mileage is likely secondary to 1) your 09 truck is more heavy than the 2000 2) the 09 has more power. More power = more fuel consumption. Of course, you also have to factor in what gears you have.

 

the old truck was actually 3:73 and the new is 3:42 and I do realize it is a heavier truck and more HP but right now it is about 8 to 9 mpg less than the old truck

 

The 6l80e has a taller OD I believe so it should help even things out. The winter blend gas also really hurts MPG.

 

I did notice that as soon as you hit any kind of a grade the tranny will shift back a gear and only goes into v4 mode occassionaly

 

8 to 9mpg? So your old one got 17-19 and your new one gets single digits? Even when I beat on my 6.0L/6speed I get 13.

I hate the rattles in mine (down to door rattles finally) and I'm not pleased with the seats but no one seems to make decent seats anymore. Lear definitely farked up on the GMT900, in the olden days they made some nice seats.

 

I was getting 15 to 17 mpg and with the old truck I would get 21 to 23 so maybe more like 6 to 7 mpg less I have been told that after a few thousand more k it should get better