Poor gas milage

[JimW]

Good day!
My average mpg is around 13-14mpg. I have the Five Star tune for daily/tow 87 Octane and a cat back exhaust. I know I have bigger tires but seems like a lot of people on the forum are getting at least 18mpg.
Should I "try" to contact Five Star about this?
Is there anyone else getting the same mpg as my truck?

Thanks

 

[duneslider]

Is that around town/mix driving? I only get 18+ on long highway drives. My around town average is 12-14ish.

 

[Lou Hamilton]

I have been keeping a detailed spreadsheet of my gas mileage since I got mine.

I bought it with 75 miles on it so my spreadsheet takes that into consideration and doesn't count those. Between 12/11/19 and 4/26/22, I have accrued 42,299.1 miles. In that time, I have averaged 16.120 MPG, 338.4 miles per tank, 20.936 average gal/fill-up, $71.16 per fill-up, avg. cost per gallon is $3.40, and avg. cost per mile is $0.22. I traveled 14,189.6 miles in 2020; 21,832.7 miles in 2021; and 6,351.8 miles thus far in 2022.

When towing on a highway, I usually get 12-14mpg. When not towing on a highway, I usually get 18-20mpg. I never go more than 5 over the speed limit (unless passing I might go a bit more) and don't rev or race off the line at lights or stop signs. I'm a relatively conservative driver in that respect. I have not really calculated straight city driving, but it is probably in the same 12-14 mpg as if I am towing. My town has a lot of lights and stop signs (inner city style atmosphere).

 

[Pawpaw]

Good day!
My average mpg is around 13-14mpg. I have the Five Star tune for daily/tow 87 Octane and a cat back exhaust. I know I have bigger tires but seems like a lot of people on the forum are getting at least 18mpg.
Should I "try" to contact Five Star about this?
Is there anyone else getting the same mpg as my truck?

Thanks

I'm sure you corrected for the tire height. If not it will throw mileage off a bit. Roughly 2 mph less for every inch of tire height added. This will show less mpg's then what you're actually getting.

 

[Deadman]

Typical for lift, big tires, spacers. Take that stuff off and watch you milage come right back. Theres a reason the factory doesn't sell them that way......

 

[Lou Hamilton]

Typical for lift, big tires, spacers. Take that stuff off and watch you milage come right back. Theres a reason the factory doesn't sell them that way......

Ironically, my Average MPG is exactly the same before and after my lift, bigger tires, and removal of front air dam -- 16.1 mpg. I just added those fields into my spreadsheet because I was curious.

Well, I guess technically it went down -- Before lift = 16.135 and after lift = 16.112.

 

[JasonH]

Heavier tires and 87 octane reduce your mpg. I lost around 1 - 2 mpg going with all terrain load E. I gained 1 mpg going with premium instead of regular. My around town mpg usually averages between 15 - 17 depending on the highway/city mix. One of the reasons I started using premium is that I noticed better mpg, which effectively reduced the premium paid per gallon. The vehicle is a heavy brick...there's not really much you can do apart from being gentle with the gas pedal, staying under 65 mph, and minimizing stop/start. I got over 20 mpg when I drove like there was an egg under the gas pedal. It's actually pretty amazing what a vehicle this size can do when you drive to maximize mpg.

 

[keny01998]

I average 16 mpg with new Michelin Defender and 87 octane gas. Highway is about 20 mpg so I'm satisfied. Whenever I tow my 4000 lbs boat, the mpg is like 10 or less.

 

[JimW]

Yes that is my overall average. Thanks of the feedback.
I would like to run premium gas but it's so expensive right now. Five Star told me the 3.5 really does better with premium even without a tune. I'm sure that would add to the mpg.

 

[Lou Hamilton]

Yes that is my overall average. Thanks of the feedback.
I would like to run premium gas but it's so expensive right now. Five Star told me the 3.5 really does better with premium even without a tune. I'm sure that would add to the mpg.

I have always run Premium. My reason was not straight performance, but because I tow and that is the recommended fuel grade Ford says to use when towing.

 

[Calman2k]

Good day!
My average mpg is around 13-14mpg. I have the Five Star tune for daily/tow 87 Octane and a cat back exhaust. I know I have bigger tires but seems like a lot of people on the forum are getting at least 18mpg.
Should I "try" to contact Five Star about this?
Is there anyone else getting the same mpg as my truck?

Thanks

You might be able to check and see if your speedometer is off. When driving on the freeway pull up your google maps and compare the GPS speed to the speedometer on your truck. If they don't match it could throw off your mileage.

 

[Lou Hamilton]

You might be able to check and see if your speedometer is off. When driving on the freeway pull up your google maps and compare the GPS speed to the speedometer on your truck. If they don't match it could throw off your mileage.

I like the app Speedbox. Not sure if it available as Android, but it is available in the Apple App Store.

 

[purevw]

Assuming the odometer reads from the wheel sensors or even any other sensor within the drive train, the odometer mileage will not be correct if you vary away from OE tire size. Someone stated 2mph per 1" of tire size. My pickup is off by 7mph by going only slightly larger than OE at highway speed. There are plenty of free calculators online where you can enter your OE and actual tire sizes and get an accurate estimate of the speed / odometer variation caused by the modification. If your odometer shows you traveled 200 miles, but you actually traveled 230, then there is no way the odometer can be used for mileage calculation. I can't speak for Apple products, but if you use Android, DigiHUD pro speedometer is a good digital gps speedometer / odometer, with full features. I use the paid version (3 or 4 bucks). It also gives you the option of placing your phone on your dash, to cause a heads-up display to be reflected off of your windshield, but I have concerns with leaving a cell phone in direct sunlight for long periods.

 

[Pawpaw]

Checked my speed with one inch taller tires and GPS read 69 mph when dash showed 70 mph. Close enough for me!! Usually 2 mph less for every extra inch of height. Some factory speedometers show 2 mph higher than you're actually going.

 

[1111ExpyEL1111]

It's a large SUV. I'm sorry but what did you expect? Best I've got on our 16 Expy is 20.1 highway at 55 mph and no AC. Normal highway 70 mph is right around 18. City is typically 15.

 

[JimW]

You might be able to check and see if your speedometer is off. When driving on the freeway pull up your google maps and compare the GPS speed to the speedometer on your truck. If they don't match it could throw off your mileage.

Yeah my speedo is off by 5mph so I Know that effects the milage a little also. 5 star was suppose to adjust the speedo but they can't get it right after multiple calls....

Of course, the tires effect the mph. I had 33's on my 07 Escalade with the 6.2 and had about the same mpg.

I do add fuel infector cleaner and octane booster from time to time to help. Today i have around 15.5 mph(driving easy) so after I adjust for the tires that would be around 18-19 mpg so I guess that's not bad with the larger tires. Thanks for the feedback!

 

[Deep8174]

The expy is horrible in gas mileage around town. Hwy is decent, but in my geographic area and the way this city is hilly I average about 13 mpg as well.

 

[Lou Hamilton]

The expy is horrible in gas mileage around town. Hwy is decent, but in my geographic area and the way this city is hilly I average about 13 mpg as well.

I get about the same in city as my previous 2011 Honda Pilot. Highway is about 2mpg less than the Pilot.

 

[Fozzy]

Usually the tune is the problem, makes you want to put your foot in it more. But with 35ish tires that sounds about right. I average 13-14 combined with 35x12.50x20's driving it like gas is free.

 

[JimW]

Usually the tune is the problem, makes you want to put your foot in it more. But with 35ish tires that sounds about right. I average 13-14 combined with 35x12.50x20's driving it like gas is free.

Yea that's the problem driving it like gas is free...haha