Like they said with driving habits. Good driving habits and I will had GOOD maintenance as well. My first truck was a 78 chevy (350ci TH350) that had been in the family with the best milage being around 12. When I got it I went through it cleaning all I could and replacing any dirty filters. Make sure the catalytic converters aren't clogged as well. I ended up getting 16-17 mpg in "Old Blue" when I was in college and all I did was drive and cruise in town (gas was $1.25 also lol). But the point is Good driving, GOOD maintenance and maybe a few quality aftermarket parts and you will see a significant increase in mpgs.

 

Agreed, Filters, filters, filters.

 

yeah i get an average of 13.5 right now and i use cruise control everywhere well i drive around 20 miles straight on a highway to get to school and i drive 55mph on the highway whole way on cruisecontrol. and when im in the city i dont pound it. its just killing me and your getting 19mpg with a 1500HD crewcab 4x4?? cause my dads 2wd base Crewcab averages 22mpg. I dont speed im used to going slow in my tractor trailer so idk im just trying to find the best way to improve gas right now. I just did an oil change and i am bout to buy a Cold Air Intake and hopefullyl a exhaust soon and a bed cover im hopoing to pull 15 if possible from all of that. but 19mpg???? that i would love to see on my truck.

 

What size tires do you have? Did you already mention that? If you have huge tires that could also change the mileage. I'm getting 19 out of my 1998 if you were referring to me getting the 19. It's a 2wd, extended cab, long bed. I'm not sure what the problem is with your truck. You should be getting a whole heck of a lot more than 13. That sucks. You need to get something done, my 454 could probably get that if I drive 55 everywhere.

 

yeah i have the stock tire size on my truck. i heard these 1500 Heavy Duty 4x4 models get horrible gas milage compared to everyone else. I heard since its a model for towing or hauling alot and also since it has the 6.0L motor it is a gas guzzler. im just trying to fine better ways to improve it a lil better. If you have the 2wd model that is also alot better gas milage also. all 2wds get better gas significantly. (IMO) i have had 2wd Dodge Ram and a 4wd and my 4wd got a good 4-6mpg less then my 2wd so im used to that. Its just that im hoping theres away to get a lil better gas out of her lol. just 2 more mpg and ill be happy

 

also would the GMC model be different majorly in economic wise compared to the chevy model. Since i forgot to mention i have the GMC Sierra 1500hd 4x4 not the Chevy model but i figured they were just the same truck.

 

Know there is know difference in the GMC vs the Chevy when it comes to economy. Instead of using the cruise control try just driving it with out the cruise. I have heard that makes a difference and I treid it and it did seem to help... I drive 25 miles to work and back. The bed cover really only works on the Freeway. Around town it is just dead weight if it is the hard cover. A softtop is way lighter. However according to MythBusters the hardcover does not help... I personally have never seen that episode, but I feel the cover does help on the freeway. I have hte softtop on my GMC Sierra, but I prefer the hardtop.
I have the TB bypass done on my truck and it did seem to help on power wise, but not in the MPG, but it did not hurt it either.
As far as the TB spacer; we put 1 on my mom's Avalanche and I feel it actually hurt it performance wise. MPG I feel like we did not get a good check, because of my mom's driving and MPG checking. Some people say they help and a bunch others seem to say it is a paperweight. If you decide to get a spacer just get a cheap one.
what kind of air filter are you running; paper or a K&N or something?
I would do an exhaust system or muffler 1st then a CAI.
And a TUNE! I have heard everyone has gained when it comes to a tune. I have 2 handhelds only, because of the deals I have gotten on them, but I advise a tune. That is next on my agenda.

 

^ yeah my goal is 15mpg so hopefully i figure in the long run it will help, just going to go buy a exhaust probably today, and i was going to go with the kandN CAI, then i didnt know how much the tuners really helped on a gas model i know on the diesels they are amazing since my cousin has a F250 7.3L diesel and he gained over 3mpg more with the tuner. so i was skeptical about the tuner thing. but thanks for the advise. im planning on buying a soft top cover for my truck and hopefully see where it gets me too. gotta go to the store today and buy some goodies i guess.

 

Check the pressure in your tires. That could help the mileage if they are low.

 

switching ur air filter to a K&N or getting a cold air intake, throttle body spacer, bed cover and programmer like a diablosport predator are pretty much all guaranteed to work. The programmer can either help or hurt u depending on what u do with it... i installed a K&N coldair, bed cover, throttlebodyspacer, and flowmaster true dual exhuast on my 08 silverado (rated at 19mpg highway) saw an increase to about 25 when i programmed it for fuel economy, BUT when i changed the programmer settings to tune for power instead I only get a measly 10.8 mpg (worth it b/c of the hp difference)... in my opinion the intake and programmer can give the greatest gas mileage increase, just be careful how u tune it