Wow if you've done all that and your STILL only getting 10-11mpg, I"m gonna have to say it's driver error thats causing poor mileage. When I drive my hummer, if I let the truck shift over 2100-2200, its because I"m going up a big hill or I'm passing (which isn't often I floor it still). When I drive, I stay neck-and-neck with tractor trailers. If you are driving that thing like an indy car, it's gonna suck gas. I'd keep rpm's around 2k or so. Big v8's do NOT like to rev high (for saving gas anyhow). They produce torque at low rpms, so thats where your gonna wanna keep the truck running.

 

I've run my own testing on high octane and it does squat for millage. Your best improvement to your gas millage is just your driving. For the first time ever this morning I broke the 14mpg barrier I had been bumping into for a while. I hit 16.2 mpg on my trip in. Normally this early on a tank I'm at about 12.4, but this morning I was just really conservative in my driving traffic wasn't very heavy and I was using the gas so sparingly I felt like one of those hypermilers. I don't have any pcm tune but my tires are at 39psi all around. The pisser part is after the 8 floor climb in the parking garage I was back down to 15.6 mpg which is still markedly higher than I've been able to do before but I was really looking forward to finally being at the peek of fuel efficiency.

 

If you are asking me, my best economy is on the highway on long trips & driving sanely. Back roads & City is not anywhere near as good but still is not too bad for what it is.. J

 

FWIW, I currently run Procomp AT's on my current H2, but ran BFG, AT tko's on my other H2's... They got me the best traction & MPG.. J

 

on my h2 2003
i have stock tires , airraid air filter and a new tune up ,air in tires at 38psi.
i drive back roads and city driving . 52 miles a day .
i have been avg 13.2to 13.6 mpg i was going to try a tuner
but i was wondering maybe the past owner may have already did this because my mileage is better than what i see on the board and i dont want to mess it up . i am using 87 std gas , i will be adding a roof rack so i know the extra weight will drop my mpg a little , i hope not that much .
i would like to get the mpg a little higher but i dont know the upper limits
and what other people are getting and whats realistic, i use the cruise control most of the time if i can . mike

 

I keep it between 1800 - 2000 Rpm, Slow off the line, using cruise as much as possible. Seldom over 60, 65 max. There has been a lot of road construction here and I spend a lot of time idling and that's where my mileage is being killed. Going to do a log this week and send it back to Lew and see if he can do anything with it. 5.38 gears with a front locker are next on my list.

 

I'm tapped of ideas man. I'd say do basic maintenance (if this hasn't been covered already); new spark plugs, new fuel/air filter, new synthetic fluids in everything, etc. Dunno if there are chassis lube points on the 2, but see if there are. Other than that, I"m not sure there's much you can do brother.

 

It's hard to explain. Timewise...1hr commute...40 min city ...20 min. hwy
distance....30% city.......70% hwy. Just get stuck in a lot of stop and go traffic with big hills.

 

Then I would say your getting pretty good mileage, that 40 min in stop n go traffic is whats hurting you. 10mpg isn't bad considering your driving conditions. I have a buddy who lives in the city and he's getting 7.8 to 9.0 mpg which is really bad. Every time you stop the H2 and then have to get it back up to speed that thing sucks a lot of gas. The next time you take off from a red light watch your instant mpg on the dash it will read some where in the area 4mpg its crazy.

 

I did my usual commute today, no road construction. Up to 11.8 now. I still can't understand why others are up to 13.9 with stock vehicles. I was only around the 10 mark when I first got my H2 and I've always been a very conservative driver.