3. Oxygen sensors: Another overlooked aspect especially on higher mileage vehicles. While it may never trip a CEL, anything other than the needed a/f ratio is inefficient.
4. Brakes: While braking doesn’t improve mileage, dragging brakes can take a huge toll before a problem is spotted. There’s a reason it’s part of the inspection included in the maintenance manual of your truck. Check to ensure caliper slides move correctly and the parking brake isn’t dragging.
5. ALL fluids: So you do the oil changes, that’s great, but have you thought about things like your power steering, differential, or transmission fluid? Anything that leads to a loss of power is taking it away from creating forward motion. Keep fluids in good condition and even do UOA (used oil analysis) to ensure its condition.
6. Spark plugs and ignition: Making sure proper voltage is getting to the plugs and that the gap is within range will help make efficient use of the fuel and air in the combustion chamber.
7. Fuel system: Many don’t think about the quality of the fuel they are buying. It may be the same octane, but the detergent packages of the fuels can vary. Buying top tier fuel helps to confirm a healthy level of detergents to prevent deposits. Deposits in and on the injectors can cause an uneven spray pattern and less even distribution of the fuel in the mix. Along with using quality fuels, there are several fuel system cleaners on the market. All of these products are not created the same. PEA (polyether amines) is a class of cleaners that safely and effectively clean fuel system and valve deposits and is the gold standard in the industry. I won’t endorse one product over another, but a search of PEA will give you an idea of which to look for.
8. AC usage: The AC compressor adds drag. It’s been found in lower speeds opening the windows creates less drag than running the compressor, when speeds increase the drag becomes greater from wind resistance and the AC should be used.
9. Weight: It takes more energy to create motion if the mass is greater. We drive heavy trucks, but keeping things that are not needed like “Why do I still have Joe’s barbells in the back of my truck??” out of equation helps.
10. Air filter: Notice I left this until the end of the list. Very rarely in normal conditions do we see air filters that are restricting flow. Most people are pretty good about changing, and usually over change the air filter.

MODIFING for mileage: This is a slippery slope. If you do it solely for mileage, you may end up disappointed. Don’t expect the mileage claims from most manufactures. Do your calculations based off of what real world you may see and the time for return. Doing a mod that takes 100,000 miles to recoup the cost doesn’t make sense to me. Do it for your enjoyment and let the mileage be a bonus is how I go about mods.
1. Cold air intakes (CAI): One of the most asked about modifications. In theory it seems like a good idea, less restriction will mean more power to create motion. While this is true, we have to look at what you already have in the stock system. Most stock intakes on F-150’s draw air from the fender well. It’s really a good location as intake temperatures are near ambient. No shiny CAI filter can lower intake temperatures beyond ambient, only an intercooler can cool the intake charge. Now on to restriction of filters. The stock system, even horribly dirty, can flow enough air to supply the motor. Some slight gains can come from a less restrictive filter, but usually at the cost of filtration. It depends what value you put on the rest of the internal components to allow more silica particles through the filter verses a slight restriction. There are also modifications that can be done to the stock system to maintain a high filtration level while easing restriction. Most famous of these modifications to the stock system is the “Gotts mod”.
2. Programmers: Programmers with the proper tuning can give the greatest chance at improving mileage, but also come with a cost. Even on a stock vehicle, tunes will give a better driving experience and custom tunes allow modded trucks to take full advantage of those mods. Many turn to “mileage” tunes to try to improve mileage. These tunes often times limit power however. This limited power can actually lead to worse mileage in some situations. A custom tuned device gives the best chance to see a gain. There are several trusted tuners that write F150 calibrations. A tuner will adjust a/f trims and maps to maximize efficiency. They do so by taking out the “compromises” that factory tuning has to do to please everyone, and adjust to your driving style and your specific truck. Be wary of devices that claim +4mpg and 70hp, these are scam items that aren’t actually programmers. Expect a quality, custom tuned programmer to be in the $400 range. Mileage gains can be good, but may take a long time to pay back.
3. Exhaust: Exhaust modifications are seldom to see gains as most do so for sound. Romping on the throttle has a negative effect on mileage. Systems with headers can gain performance, but little on the mileage side. See my exhaust education thread for more details on exhaust in general: https://www.f150forum.com/f11/exhaus...re-myth-78102/
4. Electric fans (Efans): Efans are a popular mod for 2008 and earlier trucks. The 2009+ trucks came with this modification from the factory for the reason of improved mileage. Replacing the stock fan is a double edged sword. While it can yield decent mileage gains; quality connections, fans, and controllers should be used to avoid issues. Mechanical fans are almost worry free, efans done incorrectly can be a thorn in the side.
There are several other modifications that can be done, but have varied results impacting mileage. These include things such as tonneau covers, under drive pulleys, and throttle bodies. One modification that has no proven gains in fuel injected operation is the throttle body spacer. On the dyno and in the real world it has no proven gains. Here is a list of other “mods” tested that show no gains according to the FTC and EPA: http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut10.shtm
5. Gearing: Many choose to go to larger tires and wonder why mileage has dropped. Beyond the obvious of adding additional resistance, the speedometer is also changed along with effective gear ratio. Changing the speedometer to read correctly, and thus make correct mileage calculations is a good first step. This can be done via a reflash at the dealer, or by any quality programmer. The issue still remains that the effective ratio has changed. Changing gears is costly and usually doesn’t make up for the mileage gain if any is seen, but your transmission will thank you by lasting longer. In general, gears shouldn’t be done for mileage if the tires, rims, and ride height is stock.


I’m sure I’ve forgotten several points and made several spelling and grammatical flaws, but I’ve spent a few hours looking at a computer screen so frankly I really don’t care. Feel free to PM me if you feel I made an error or want me to add more to this mileage excerpt. I’d like to thank bobkyle2 for alerting me to the thread and inviting me to share my automotive knowledge.