Yes the mileage sux but the engine rocks!
The new GM 8. 1/496 is an awesome engine. I have
one in a 2001 GMC Yukon XL (Suburban) 3/4 ton
4x4. It has (gasp) 4. 10 gears, and on a highway
trip of about 300 miles, I calculated 13MPG. It
routinely gets 11-12 MPG combined city/highway.
The GM guys did their homework on this one. Even
the sound eminating from the exhaust is similar
to a Z-28 (not quite that loud but it sounds
great!) If I had a choice it would have 3. 73's.
Still, a neighbor of mine has a new Chevy 2500HD
2WD crew cab, short bed, with the 8. 1 and Allison
trannie, 3. 73 gears, and he is tired of the gas
mileage, about 12 MPG.
As for towing, I have not yet had a chance to
hook up my 25' Baja Outlaw (6,200 lbs including
trailer). One thing I DO know, is that I towed
the same boat/trailer on a 360 mile trip with my
previous RAM, a 3500 QC 4x4 ETC/5spd and was
happy to calculate 13 MPG towing. Cummins power
rules!
If I had a choice between the 8. 1 and the new
Duramax (which is not available yet in the new
Suburban/Yukon XL), the mileage would be a
concern so I'd probably spend the extra money
and go Diesel.
-Chris