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first small road trip. terrible MPG

ct_corey

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SMJ24 Enthusiast

SMJ24

Posted
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Every Sunday my son plays in an indoor lacrosse league, it is a 39 mile one way trip with approx. 35 being highway. Last Sunday I was early so I set the cruise control to the posted speed limit of 55 and 60 mph and maxed out at 24.1 mpg for the trip. This week I drove it like normal, still using cruise control but set at 70-75 mph and maxed out at 19.1 mpg.

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thewhitestallion Senior Enthusiast

thewhitestallion

Posted
Posted

Well there are a lot of variables that come into play. Could be the gas, could be the terrain, could be the drag from your lift, could be your speed. In all honesty in my opinion it is all of those factors.

 

When I am on a road trip, if I go over 70mph then I know not to expect great gas mileage out of the truck. Sometimes the truck surprises me but between the wind resistance, terrain and higher rpms your chances of good mileage drops tremendously!

diyer2 Senior Enthusiast

diyer2

Posted
Posted

Cruise works well on flat roads, not so well on hilly terrain. On flat it will not down shift as much trying to keep up to speed.

Krusty Enthusiast

Krusty

Posted
Posted

In my Duramax 2500HD 4x4 CC Standard box I saw 19 mpg avg overall on empty hwy trips hand calc driveway to driveway. A perfect trip at 65 mph and 1,600 RPM peak torque would net 20-21 mpg.

 

But these V-4 switching engines ain't no Duramax - I know that going in - and don't expect the same outcome.

 

:chevy:

Heavy 5.7 Enthusiast

Heavy 5.7

Posted
Posted

Every Sunday my son plays in an indoor lacrosse league, it is a 39 mile one way trip with approx. 35 being highway. Last Sunday I was early so I set the cruise control to the posted speed limit of 55 and 60 mph and maxed out at 24.1 mpg for the trip. This week I drove it like normal, still using cruise control but set at 70-75 mph and maxed out at 19.1 mpg.

If it's "normal" for you to drive 10-15 mph over the posted speed limit you may want to invest in a watch or day planner. lol.

Brian S. Enthusiast

Brian S.

Posted
Posted

Nothing is "killing" the "fuel economy", that's just the way it is.

 

I did a year with the 4.3l Ecotech and got 17.4 mpg on a 3.42 geared 4wd dbl cab.

 

I've done over two years with two different 5.3l Ecotech 3.42 geared 4wd dbl cabs and got 16mpg overall.

 

The only time I've noticed you can get 20mpg (or more with the 4.3l) is cruise on 60mph.

 

I think these "Yes! I'm getting 20mpg with my half ton pickup truck (any brand) are basically lies or people posting about trips on flat road at 60mph with cruise on.

 

It's also intuitive that levelling trucks would lower mpg, they have big, flat fronts that would drag more with pitch adjusted to perpendicular to the road. It's no mystery why every sports and racing car on the planet has a pointy front end and sits low to the ground.

tnchevy Senior Enthusiast

tnchevy

Posted
Posted

The OP is driving near 80 mph and has a 1.5 inch level ( and probably more aggressive tires to go with it) in a V8 truck and is complaining about fuel mileage in the mid teens???? Drop your truck back to the factory level, quite driving well over the speed limit, and if you have bigger/more aggressive tires then put the factory size and style on it and you will get around 20 mpg.

Z45 Senior Enthusiast

Z45

Posted
Posted

Once you get over 65 mph the mileage is going to go down, more wind resistance. On a recent trip I drove 300 miles on 2 lane blacktop at 60-65 mph and I was getting 23.4 mpg. The next 280 miles were on x.way and I was doing 70-75 and mileage dropped to 22.1.

ct_corey Enthusiast

ct_corey

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The OP is driving near 80 mph and has a 1.5 inch level ( and probably more aggressive tires to go with it) in a V8 truck and is complaining about fuel mileage in the mid teens???? Drop your truck back to the factory level, quite driving well over the speed limit, and if you have bigger/more aggressive tires then put the factory size and style on it and you will get around 20 mpg.

Stock tires. If they were larger I would have mentioned that but thanks :nopity:

truckguy82 Senior Enthusiast

truckguy82

Posted
Posted

I drove 330miles back and forth a couple times a year, I set the cruise control on almost exactly 75mph on 65mph highways. I average 21-22mpg there and back like clockwork. Stock '14 6.2

Havvkeye Enthusiast

Havvkeye

Posted
Posted

If it's "normal" for you to drive 10-15 mph over the posted speed limit you may want to invest in a watch or day planner. lol.

 

Why? Are you assuming people only speed when they are late for something? That is pretty ignorant.

FreeAmerican Enthusiast

FreeAmerican

Posted
Posted

Wind resistance is exponential. Winter gas sucks too, as well as it takes longer in the winter for your truck to reach operating temps. Also have you checked your tire pressure. Cold weather impacts that too and can cost you some mpg as well.

 

Add a level and you have your answer.

 

I do notice I get better power (butt dyno) and def better mpg running higher octane gas and I turn the grade braking off.

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