What gives these pigs better fuel economy?

[akthrillseeker]

I own a 96 Jimmy. I was getting 13mpg. I spent $500 on tune up and fuel repairs. It increased my mpg to 16. I was under my vehicle messing around and noticed that the front diff was locked in (drive shaft didn't spin freely). I checked on my friends 98 blazer and found hers was not locked in (drive shaft spun freely). My Jimmy was not engaged in 4X4. I had it checked ant the engaging cable for the front end was broken. $450.oo fix. Now the Jimmy is getting 21mpg.

[turbovanman]

My fiance is driving it now, she's averaging 20 mpg, so maybe she's lighter on the gas than me??? I also installed a cold air intake so we'll see if I can squeak out some more.

[Bryan Burkhalter]

Old thread, yes. But MPG's are near and dear to my heart. I was under the impression that a CAI would improve power, but not necessarily MPG's? I thought that warmer air coming in would improve the fuel economy?

My truck is a 2000 GMC Jimmy, 2wd/4dr with 125K miles. I haven't done anything as far as performance parts goes, I just really baby the truck. Has stock intake/exhaust, standard OEM brake replacements, new sealed hubs. No throttle body spacer, or performance chip mod. I have made several trips recently from Mississippi to Michigan, roughly 1100 miles one way. I normally get about 270-290ish miles to the tank between fill-ups on the highway. My latest trip, I went 346 miles between a particular fill up. The next fill up came at 300 miles, with no real change in driving habit. I kept cruise control on both times as much as possible. Being a man, I'm by nature fairly OCD(obsessive compulsive) so I was watching my RPM's like a hawk. My RPM's stayed fairly stable at about 2100-2200, excluding random speed ups to pass or hills here and there. I have no explanation why there was such a dramatic difference in fuel economy between the tanks. I'm leaving again this coming tuesday from Michigan to Mississippi, so I'll try to get a more thorough picture of the travel and post it(ie-outside temp, road conditions, accessories running, night-vs.-day travel, PSI in tires[supposed to be picking up new wheels/tires on monday, so guessing that may affect mileage too])

[Bryan Burkhalter]

A bit late on the reply, but here it is:

Excluded the drive between Detroit and roughly Tennessee, since it was snow/ice, the other lengths afterwards I only averaged 300miles per tank. It was pretty much all night driving, with outside air temp being in the 30's until I hit Mobile, which is directly on the gulf coast, and even then, it only warmed up to the mid 40's. I never once had the pedal floored to pass a vehicle. I specifically only passed people on my cruise control, and if I had to slow down, I consistently let my cruise catch me back up to speed, so that the acceleration was controlled by the comp., and not my foot. I'm still keeping an eye out in city driving for habits or conditions that improve/impact my MPG. Nothing noticeable as of yet, except for keeping my RPM's at or below 2K as much as possible.

[ZL1power69]

Thread is almost 2 years old. Using the cruise under daily driving conditions will most likely not improve fuel economy. The computer uses to much fuel to bring the truck back up to speed. A person is capabile of using much lighter throttle inputs.