Fuel Economy

[rffg]

I am seriously thinking about obtaining a 2001 2500HD with 8.1 engine and 5 Speed Allison Tranny. I has 19,000 original miles. It should be able to pull my boat/RV with no strain (and probably the factory that built them). But, when not pulling I may have to use it as everyday vehicle. Will gas milege be awful, bad, deplorable, ugly, fair? I drive carefully and usually keep my vehicles at 2000 rpm while on the open road. City driving (stop and go) will be bad I'm sure. I just want to know what to expect. Any responses regarding your experience will be appreciated.

[djpbaby]

Aweful gas mileage! Most people I know that have gotten one get about 8 to 12 miles a gallon at best. The tow truck guy I know with that engine gets 6-8. That is a 498 cubic inch gas guzzler. I don't even know why they made that engine an option (you used to and can still get a 502 crate motor from gm, but they never offered it in any vehicles). Some people say that the money they will save by going with that engine instead of the 6.6 Duramax is worth it to them. Maybe, that's if you only own your truck for less than a year or so (the duramax is an easy 3000 bucks on top of a 8.1) But seriously, with gas prices, you cannot afford not to get a desiel motor when your looking for towing power. They spin at less than 3000 rpms and have 3:73 rear ends (the 4:10 is not available in a desiel) and they are torque monsters. If you invest 800 bucks for a chip, you will have a motor that will produce over 450 hp and 700 ft/lbs of torque! The allison will not accept any more torque than that and even that's on the edge. The only vehicle that my brother has ever lost in a race to with his 01 duramax that he's had for 6 months was a seleen cobra mustang and he wasn't that far ahead. And the best part, 14 mpg at worst. We got 15 mpg pulling a 7000 lb boat through a steep canyon pass and then went 85 on the freeway for the remaining 200 miles of the trip.

[dcg]

I have a 2004 2500HD with the 8.1 and Allison. It now has almost 6,000 miles and according to the information center on the dash the mileage is 13.2 since the engine was started the first time.
I tow a 20 foot bass boat through mountains and round trip is in the 12 -14 mpg range. Around town with the air conditioning on most of the time I have been averaging about the same 12-14.
The truck has the 36 gallon gas tank and gets around 500 miles on a tank.
The only modification is a K&N air filter.
I don't consider these numbers outstanding, but I also didn't order this truck for the mileage.