7 Ways to Boost Your GMC's Fuel Economy



You didn’t buy your GMC truck for its fuel economy, and that’s okay. However, there’s no reason you shouldn’t get decent gas mileage when driving your pickup. Here are seven tips will help you get the most out of a tank of gas.

1) Check Your Oxygen


Oxygen sensors (aka O2 sensors) are an integral part of your air/fuel control system. When they go bad, your vehicle's engine control module (ECM) won’t know if your engine has the right air/fuel ratio, and will therefore run rich in order to make sure that there's no risk of detonation (which can be destructive).

Therefore, replacing old O2 sensors that are setting check engine lights from time to time will keep your engine from running too rich. This will save gas and reduce the odds of a backfire These sensors are usually less than $100 a piece and most people can change them at home.


2) Check Your Plugs


Spark plugs are another part that can often go overlooked in the quest to maximize fuel economy. While spark plugs wear very slowly, the electrodes on the spark plug can become fouled with carbon deposits that diminish their effectiveness. A spark plug that isn't sparking at 100% can lead to incomplete combustion, which typically leads to a drop in fuel economy.

Additionally, as a spark plug electrode wears normally, it can start to "lose" the correct amount of gap. If the gap becomes too large, it can lead an engine to "miss." If the gap becomes smaller, it can become less effective at igniting the air-fuel mix, leading to incomplete combustion.

Fortunately, spark plugs are inexpensive (a few dollars each) and most mechanically-minded people have no problem changing their plugs at home. If you find that your plugs are heavily fouled - or seem to become fouled after only a few thousand miles - this may indicate a larger engine problem...so it's a good idea to pull your plugs and take a look at them from time to time.


3) Sweat the Small Stuff

Will you really shouldn't need an excuse to service your GMC (you're probably doing it for all the right reasons already), staying on top of maintenance can boost fuel economy.

  • Air and fuel filters are important to engine efficiency. These filters are inexpensive and relatively easy to change, and in the case of air filters, an after-market performance unit can often improve fuel economy
  • Synthetic oil can reduce your engine's internal friction, improving fuel economy a percentage point or two. However, using synthetic oil on an older engine can sometimes cause small oil leaks to become much more noticeable, so use caution.
  • Keep an eye on tire pressure — an improperly inflated tire will result in drag and decrease fuel economy.


4) Tire Tread and Fuel Economy

One of the easiest ways to improve a truck's fuel economy (particularly on the highway) is to mount a set of all-season tires. Most tire shops will refer to these as "highway tires" or "car tires" when you mount them on a truck, as they tend to be underwhelming off-road (indeed, some all-season tires are downright terrible on the trail). However, all-season tires have lower rolling resistance than all-terrain tires, and that translates into better fuel economy.

If you use your truck off-road only occasionally, a set of all-season tires might be a good choice.

NOTE: Beware low rolling resistance (LRR) tires. While they can definitely improve fuel economy, they tend to sacrifice traction in the process. A truck with LRR tires may not be as stable in inclement weather, may not stop as easily, etc. However it will definitely save gas...some LRR tires can improve truck fuel economy 1-2 mpg all by themselves.


5) Get Rid of Any Extra "Gear" You're Hauling Around

When you add weight to your GMC pickup, your trucks' engine has to work that much harder. Adding a mere 100 pounds of gear to your truck can decrease fuel efficiency by as much as 2%, a pretty significant decrease. What's more, weight can add up quickly:

  • Bags of sand or old tires are often hauled in truck beds year round, as they aid traction in bad weather. However, they can easily weigh 50-150lbs
  • A box of clothes and books that you’ve been meaning to donate might seem like no big deal, but that 25lbs box could cost you a couple of dollars every time you fill-up.
  • Hauling around a set of tools and battery jump box "just in case" isn't a bad idea, but these items can easily weigh 40-50lbs. Removing them from your truck might save you a few dollars a month in gas.

Finally, exterior accessories like winches, steel bumpers, grille guards, step bars, fifth wheel hitches not currently in use, etc. can all add up to dozens or hundreds of pounds. While many of these accessories are helpful or necessary, it's important to understand the impact they have on fuel economy. If you add a bunch of these extras to a new truck, don't be surprised if your fuel economy goes down.


6) Break-in and Reset


Speaking of new trucks, most GMC owners find that fuel economy improves once an engine has a few thousand miles of use. This is partially because new engines need time to properly seat, but mostly because modern trucks have engine computers that learn and adapt to the driver. While this "learning" is almost always a good thing - the truck adapts to your desired shift pattern, average travel speeds, etc. - there are situations where truck owners notice that a truck's fuel economy gets worse over time.

If you find that a new truck is getting progressively worse fuel economy the longer you drive it, it might be a good idea to reset the engine computer. You probably want to talk to your local GMC dealership about it before you begin, but it's not unheard of for truck owners to disconnect their battery for 30 minutes, re-connect, and see their fuel economy improve.


7) Get A Tuner


The factory programming of your GMC isn’t necessarily the best for fuel economy. Your truck heads to the dealership with a tune meant to make it feel swift, shift smoothly, and operate as quietly as possible. After-market engine tuners promise to improve fuel economy (or performance) by changing fuel maps and shift points. While the specific fuel economy improvement will vary with individual models, most tuners claim that they can improve fuel economy by 2 to 6 mpg.

Most engine tuners are easy to use, pre-programmed units that just take a little time to set-up. While you can often adjust the tune manually, most truck owners find that the pre-prgrammed tunes do a good job of either improving gas mileage or performance (or both). There are two things to remember about tuners, however:

  1. They often require you to use premium fuel. If you're already using premium, this isn't a big deal. But if you're buying the lowest octane available, the cost increase with premium gasoline can be substantial.
  2. They can be expensive. Some hand-held tuners sell for as much as $400, while other kits that interface with the ECM can cost $700.

Last but not least, remember that the best way to improve your GMC's fuel economy is to drive conservatively. Accelerating slowly, coasting whenever possible, avoiding high speeds, and using your cruise control can all have a profound impact on pickup truck fuel economy.