Lets talk fuel mileage and how to make it better!
 

First I will start with what I drive myself. I have a near bone stock 2008 Trailblazer lt3 with the six-cylinder. I'm all about doing little mods to get more miles per gallon. Currently I live in northeast Pennsylvania on two-lane roads in the Hills and I can achieve 18.5 miles per gallon if I Coast down Hills in neutral and rarely get over 2000 RPM. It's not the most fun way to drive but I can get just over 400 miles to a tank before I have to fill up. I've been trying to think of ways to achieve better fuel mileage. I like the way my blazer rides on the highway and also am a huge fan of how quiet it is when it is running. The only thing I have done engine wise is taken off the stock air box and purchased a eBay intake from the factory intake resonator out to the filter. My goal is not for more power but for the engine to run slightly more efficient. It is not cold air in any way shape or form but the slightly warmer air will be less dense and require less fuel to achieve it's targeted air fuel ratio. I don't know how much restriction is in the exhaust but I'm also weary about cutting off Mufflers or resonators because I don't really want it to get any louder but if there is something that is very restrictive and will allow better airflow if removed, I can entertain the thought. I also thought about possibly lowering the Blazer just a hair to possibly get slightly more aerodynamic. I know I'm driving a brick but every little bit can help. I see people leveling there Blazers by lifting the front a hair but couldn't I lower the rear and achieve the same thing? What is everyone else getting with the straight 6? What do you do to get the best gas mileage?

And before someone tells me putting the car in neutral doesn't do anything, I have a program on my phone where I can watch my fuel consumption in gallons per hour. If I am doing 60 in Drive going downhill, I am burning about .65 gallons per hour whereas if I get in neutral, it drops to .45 gallons per hour.

My wheel and tire combination is the factory 18in five spoke chrome wheels with 245 / 60 / 18 Highway Tires with roughly 38 lb of air on each corner
https://cimg1.ibsrv.net/gimg/chevrol...4c0af16bd3.jpg
142k miles, 2nd trans done 5 months ago

Pretty much just don't get on the throttle too hard, coast to red lights etc. Keep the engine in good mechanical condition. Those are the only things worth doing. I don't mess with the factory setup. The government already puts a lot of pressure on manufacturers to make their vehicles efficient, not to mention they want to sell more vehicles to economy conscious folks.

Personally, I think going down hills in neutral is stupid. It's not worth saving the dollar or whatever. It's like riding a bike with no hands. Anything that impairs your ability to respond to hazards is stupid. Driving is dangerous enough as it is.

I agree with MountainManJoe. The factory set up is about as fuel efficient as you are going to get. Basically you are pushing a brick through the air. As MMJ posted, light on the throttle, coast to signals (in other words watch the traffic). It also helps to keep the tires properly inflated - check them at least once a month. Keep it well-tuned. Coasting downhill in neutral is not worth minimal fuel savings.

If you think your fuel mileage is bad, try my '06 Ram 1500 w/Hemi. On a average day it gets 15 mpg. Maybe 17 on the highway. Of course, it has over 260K miles now.

If you really want better fuel mileage get a hybrid or an Equinox. My wife has a '14 Equinox LT with the 2.4L - she averages over 30 mpg and she is hard on the gas and brakes. When I drive it I can get over 32 mpg, but I'm a lot lighter on the throttle and brakes.

Is the little Toyota yours? If you really need to save money, then use that as the daily. Take the Blazer out on weekends or whatever.

Im not looking for a new fuel efficient car, just ways to improve what i have now. Im pretty anal when it comes to the tires. As for neutral going down hills, its not everywhere, just the long downhill stretches where big trucks have to go slow or are over a mile long. Every little bit helps! Im upgrading my front bumper and fog lights to an SS setup and will ne removing the push bar and light bar when that happens. Been thinking about a tune since these pigs run pretty rich on factory tune but until someone close by me gets hptuners, ill keep it stock.

What have you done exhaust wise? Still stock or change out a muffler or resonator?

Was mine.. sold it a year ago. It was my daily/work beater. Blazer was just for towing or nice weekends. Unfortunately, the bike and celica both got sold last summer

I think the factory exhaust is chosen to compromise between economy power and noise. You said you like how quiet it is right. I would just leave it. How much is a new exhaust system? I don't even know ... $1000? Even assuming you could achieve 1% better economy, how many miles would you have to drive to make up for the money you spent?

Why do you think it's running rich? Tuning costs thousands of dollars.

So what happens if a deer suddenly jumps out onto the highway or something and you need to get away from it, and you're in neutral?

Interesting discussion. I was wondering if a tuner would be worth the cost. I always consider time to point zero...time to pay off the purchase. $400 buys a lot of gas.

My thoughts on the air filter....what ever air volume that comes in... when cruising. the system will try to meter stoichiometric14.7 to 1 using the 02 sensors in closed loop feed back to correct for lean or rich metering....so dirty, clean, high/low air volume, dense/thin air....the system will correct itself. I would prefer to leave the stock resonator box in place as its purpose is to stop air baffling.

consider what oem manufacturers are doing for fuel savings...cylinder deactivation, synthetic low viscosity oils, low rolling resistance tires, active suspension in aero mode, active grille shutters, stop/start tech....at best all that combined, they get 4% improvement. gas direct injection seems to be a great idea.

my theory has been the more Tq you can make down low the better MPGs you will get. like Tech stated, the ecm will try to maintain a 14.7:1 ratio. so the more air you add the more fuel you need. that being said i have a 91 chevy crew cab that had a 350 tbi and got about 12 mpgs i pulled the 350 and swapped it for a cummins 5.9 (360). i then got 16 MPGs. the reasoning imo is because the cummins make all its power under 2k. the 350 you dont make much is any power under 2k. when cruising you still have to make some power to fight against the wind resistance.

i also have a chavy impala with the 3.8 super charged. it can see 30+ mpgs. max is around 53 Mph and i can achieve 29/30 going about 67-69 mph.

diesels are 30% more efficient than a gas engine.

stay off boost and you can have the best of both worlds...good mileage...power when you want it. I had a comp g and loved it.