Okay, here's my "two cents" on the mileage issue. Too many things affect mileage for there to be much point in comparing trucks, in my opinion.
1) Gearing is key, as was pointed out earlier. 3. 54s will do MUCH better than 4. 10s 10% is a conservative estimate.
2) Weight is the next biggest factor. 4x4 trucks weigh more, produce more drive train drag, and cost you fuel mileage -- maybe a consistent 5% premium over what the traction-impaired guys get. But, hey, you KNEW THAT when you ordered your truck! (or, you've been living in a cave... )
3) Aerodynamics affect MPG. Everything you bolt on your truck that isn't stock affects your MPG. This includes grill/brush guards, "nerf bars," "running boards," towing mirrors, bug deflectors, etc. The manufacturer spends big bucks in the wind tunnel to make these trucks as drag-free as possible. The energy required to push one of these "shoe boxes" through the air is incredible, and increases, exponentially, with increases in speed.
4) Driving style plays a big role. The way you accelerate, the way you apply your brakes, the speed you maintain on the interstate -- all play a big factor in MPG. Drive like you've got an egg between the go-pedal and your foot, you'll get better mileage. ('course you won't have any FUN!)
5) Local terrain makes a big difference, as does altitude. Flat-landers at sea level will do MUCH better than folks who live at altitude, in hilly terrain. I live in hilly-as-**** Atlanta. This city sits at 1100 feet, and I spend lots of time in stop'n'go traffic, cursing the fool in front of me. My buddy in Topeka Kansas, commuting into town from his farm (via interstate), is going to do WAY better than me with his truck. It's not rocket science.
6) Tune up your truck! This is something that nobody EVER discusses when the mileage horse is dragged out of the barn, and whips are passed around to the discussion participants. If your mileage sux, and other obvious factors have been taken into consideration, have your valves adjusted. I had mine done at 60,000 and couldn't believe the difference. Turns out my exhaust valves were way loose, and that simple maintenance procedure produced lots more power, and much quicker cool-down times -- with a mileage improvement of 1. 5 per gallon!
Be reasonable in your expectations. These are big, heavy trucks, typically driven pretty hard by most of us. I hear these mid-to-high 20's claims, periodically, and just shake my head. Maybe downhill, with a tailwind, being towed by another vehicle, with your engine turned off... Otherwise, save it!
My truck gets about 11-12 in stop'n'go, short trip, city driving -- the kind of driving that your diesel engine HATES being asked to do. Put her on the highway, poke along at 65 MPG (I'd end up slapping my mother, doing this kind of driving for too long... ) on a cool, calm day, and I could probably milk out, say, 18. 5-19. 0 mpg.
I drive my truck hard on the interstates, usually pushing 75-85 all the time. I think most turbo-pushers drive the same way. If I wanted to poke along at 60, I could'a bought a Ford. (Blech!) My average highway mpg is, therefore, in the range of 17. That's unloaded -- just my toolbox (which is heavy) straddling the bed.
My philosophy is "you pays your money, and makes your choices. " Drive like a 90 year old grandma, on billiard table flat real estate, for long distances and long periods of time -- you'll win the "bragging rights," mileage hero award. Big deal. Over the life of your truck, you'll save, what, a thousand bucks in fuel expenses... ?
Meanwhile, us idiots will be blowing your doors off with ecstatic grins on our faces. Yes, that's my tail lights and $200, custom-bent, (un-aerodynamic) stainless steel mudflaps, pulling away from you at near the speed of sound!
Life is short. Tune your truck up, maintain it well, then reconcile yourself to the harsh reality of who you are (guy with 200 lb right foot) and have some friggin' fun. Pay your dues to the God of energy and thermodynamics. Support "Big Oil!"
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97 2500 4x4, club cab, auto, 3. 54 limited slip, JRE 4" exhaust, Dr. Performance Fuel system (370 HP), "Twister Turbo," Geno's guages -- Boost, EGT, transmission & Rear -- MAG Hytec covers, SunCoast Converter/Transgo shift kit, Brite Box, tons o'chrome under hood, Prime Loc, EZ Drain, Seat covers, wood dash, Rancho Suspension, Warn M12000 Winch on Warn Brush Guard, Warn driving and fog lights, Hella twin back up lights, 285/75/R16 B. F. G. ATs on Mickey Thompson "Classic" rims; Linex bed liner, BD exhaust brake.
[This message has been edited by Sasquatch (edited 10-07-2000). ]
[This message has been edited by Sasquatch (edited 10-07-2000). ]