He'll be able to give you real world info/MPG #s... *IF* you can get him to respond
:
right back...
For the record, my truck is a '04 2500 avalanche. Same frame, drivetrain, etc. as the burb.. they just cut the back off.
Truck has a cat-back exhaust and I cut open the bottom of the airbox, and also has a dyno tune, in which we killed the torque management. the tune added a bunch of power and helped economy. Only other 'mod' is 265/75 A/T tires which replaced the very highway-oriented ones that came on it when I bought it.
Anyway.. empty, highway, 70-75 with some hills cruise control, 14-14.5mpg. Add a motorcycle in the bed (didn't extend above the roofline hardly at all) and 500lbs of wine, and it didn't change by more than .5mpg going to Indy and back.
Towing ~7,000 (my buggy on the open trailer) to VA and back, again, using cruise, right around 9mpg, with the truck and bed loaded with camping crap and spare parts, keeping it around 5 over. If I do the speed limit, I actually got right at 10mpg. I do not drop speed on the hills...just let it eat.
With a 7x16 tandem axle enclosed bike trailer (maybe 5-6k total), I dropped to low-mid 8's, the wind resistance was noticeable, dropping me out of overdrive on most hills. It also was mostly the same with an 8x20 enclosed.
The Class A guys with the 8.1 get 5-6 MPG moving that giant brick, so mileage can't get much worse.
What I've noticed -
Power is great, I wish i wish i wish for the Allison.. but the 4L85 isn't terrible once you adjust the grandma shifting out of it.
The ride is better than any 2500..period. (You don't have 4,000lb payload capacity like the 2500HD trucks though..whoopee.)
My engine burns 1/2 quart every 3000 miles. I run RotellaT 5w-40 synthetic, and change it when the computer says to.
Noisy lifters when cold. it goes away after a minute.
Exhaust manifold popped a stud out of the head, I hear it's not uncommon. It's not loud, but I know it's there.
Aftermarket support is slim. This isn't a 6.0.
You'll want to buy some 2" wheel spacers for the rear axle. Makes a good visual and stability improvement.
All in all, my neighbor's maggy-supercharged 1500 Avalanche will out tow mine, rides a little better, and pulls down a little better MPG. He's also spent $6k on the blower, $3k on the trans, and $1k on the rear end. No thanks. I'll stick with my big block.
