fuel mileage

[sdskinner73]

I have a 2021 gt with 355 rear axle only drive it for pleasure on dry days . My car is made of sugar and would melt in the rain!

That’s just shy of 20,000 miles. Probably 95%+ highway for me. GT 3.55 A10 non PP 400A. Honestly impressed with these cars.

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[skinnyb]

My Mach 1 is WAY thirstier than my 22 GT was. My GT (PP, 3.55 10 auto) I averaged 22-24 MPG and did an mix of city/highway, mainly a weekend cruiser. The Mach 1 (6 speed Tremec, 3.73, HP wheels and tires), I average 15 MPG. Same driving habits. I do get on it at least once every drive, I mean why have a V8 if you can't have a little bit of fun LOL...

 

[TonyNJ]

i have a 2020 mustang gt and i only roughly get 170 to 180 miles from full tank.
i feel like this is too low. or is this normal?

Are you basing your mileage just on what the FP app says or did you actually test it?

 

[Pony2015]

If you are serious about getting an answer to the mpg question (my result at end of message), it will take some work to make a somewhat valid comparison with other forum members (who would need to do the same work and post). Even so, it is still imperfect (caveats at end).

Here are the steps (yes, I know, I'm obsessively meticulous to a fault . . . ). There may be factors I've missed and always open to suggestions for improvement.

1. Calibrate your odometer: Check that tire pressure is 35 to 38 psi after fully warmed up. Adjust if needed. Find a straight, flat, stretch of road pull to the side and stop. Use Iphone GPS app (eg, GPS Speedometer and Odometer - LINK). Reset the GPS distance counter to zero. Reset your Trip 1 counter to zero. Start driving on a straight section of road (curves will throw off the GPS). Travel for 10 to 20 miles, then pull to the side, slow, and then stop just as the Trip 1 distance switches to the next 0.1 mile. Record distance driven by GPS and record what is reported on the Trip 1 meter, then divide the GPS distance by the exact Trip 1 distance. This is your Odometer correction (ODMc). Technically may need to be redone periodically as tires wear or are replaced (but I have not checked this).

2. Calibrate your Trip 1 reported MPG reading.: Check that tire pressure is 35 to 38 psi after fully warmed up. Adjust if needed. Plan a long trip (ideally 2 or better 3 or more fill-ups) of mostly highway driving (the more gallons used, the more accurate the calibration). I would aim to burn at least 36 gallons of gas if possible on this trip. At start of trip, fill the tank to the first (or second click of the pump handle auto stop), just be consistent with subsequent fill-ups and reset the TRIP1 meter to zero out miles and mpg BEFORE STARTING THE CAR. DO NOT include gallons from this first fill-up in the calculations below. If possible, use same octane rating/ethanol content (but not critical for this step). Also not critical, but I usually plan my trip with Costco gas stations in case the pump itself matters somehow (and I also use 87 octane -know I’ll get hammered for this, but I have my reasons-LINK). After each subsequent fill-up, save the receipt and write down the miles driven and mpg as reported on the Trip 1 meter. You will need all receipts to calculate the gallons used, and really only need the last receipt for total miles driven and average mpg. After finishing filling your tank on the last refill AND BEFORE STARTING YOUR CAR, look at Trip 1 and write down the total miles driven and the reported mpg. Now take the total miles as shown on Trip 1 (what you just wrote down on last receipt) and multiply by ODMc. This is the true miles driven (MILESt). Add up all of the gallons put into your tank AFTER you reset trip 1 (so don’t include fill-up right before you reset Trip 1, just gallons on all the receipts thereafter). Calculate your true MPG as MILESt/gallons = MPGt. Calculate your MPG correction as MPGt divided by the mpg as shown on the Trip 1 meter. This is MPGc.

3. Measure MPG at steady 65 mph: Check that tire pressure is 35 to 38 psi after fully warmed up. Adjust if needed. Find a relatively level and flat stretch of road on an early Saturday and Sunday morning with little or no traffic AND little or no wind and no rain or snow. Be sure engine is completely warmed up to operating temp (cylinder head temp around 200 deg F). Accelerate to 65 mph and set with cruise control. If needed, adjust cruise control to get exactly 65 mph per GPS on a straight section of the road. Now reset the TRIP1 meter while driving at 65 mph on fully warm engine. Drive for 5 to 10 miles and record the average mpg BEFORE decelerating. Now decelerate, turn around and do exactly the same thing for the trip back taking the same path and close to the same start and end. Record that average mpg and then calculate the average of the two readings.

Now calculate your true mpg @ 65 mph using the following formula: MPG65 = average of the two mpgs x MPGc.

OK, here are some caveats – probably missing some:

* MPGc in Step 2 is only valid if measured for a somewhat similar mpg as you get for MPG65. If very different, the correction may not hold.

* MPG65 may dependent on altitude. You may get different mpg at sea level than at 6000 ft elevation. It is complicated (less drag at higher altitude as air is less dense, but also less air into the engine -- less compression and thus less hp).

*MPG65 is dependent on tire pressure. If you over or under inflate your tires during the calibrations above, it will skew the results.

*MPG65 is impacted by humidity in the air (high humidity = lower mpg). So don’t do this when raining. The dryer the air, the better the mpg you will get.

*MPG65 likely decreased if outside air is cold, even if the engine is already fully warmed up. Although denser air means more air into the engine, this is likely more than offset by increased drag by driving through more dense air and possibly more load on alternator to keep a cold battery charged (especially when cruising at 65 mph). I would have said more viscous oil, but if engine is fully warmed, I think the oil temp would be more controlled by engine temp that outside air temp. If engine is cold, cold definitely decreases mpg until engine is warmed up.

*MPG65 will depend on the blend of gas you are using (eg, 10% ethanol, octane rating etc). So important to report that as well when reporting mpg.

* Any hills will lower your mpg, even if you take the same path back. You never make up downhill what you lose uphill.

* Having the AC on or setting the dial to the defrost vents (which also turns the AC on to dehumidify) will lower mpg. Best to turn these off for the duration of the 65 mph test.

*Having the headlights on will have a miniscule effect to lower mpg because alternator is doing slightly more work.

*Unnecessary weight in the car will lower mpg if hills, but if holding 65 mph on relative level path, effect should be miniscule.

*This only tests mpg at highway speeds. If you see similar mpg as others at highway speeds, it does not necessarily mean you will get similar mpg at city driving. But if your highway mpg is way off compared to others at highway speeds, then something needs attention. (It would be almost impossible to construct a similar test for city driving).

Finally, once you have measured MPG65, you can change individual variables to see the effect by measuring MPG65 with the new condition (eg, change the speed, change to 93 octane gas, or run your tires at a higher or lower pressure, etc). Just try to change on variable at a time (at least those you can easily control).

Well, there you go – if you made it this far and looking for something to do with your mustang on the weekend, maybe this could be it!

Here are my numbers:
2017 Mustang GT Performance Pack Manual MT-82
Gasoline: Costco 87 Octane with 10% ethanol (winter blend)
Elevation: Sea Level
Temperature: around 45 deg C
No meaningful wind.
Mostly level ground (between Whipple and Ralston road on Highway 101 near San Carlos, CA).

ODMc = 1.008 (Based on 40 miles driven. Trip 1 slightly underestimates true miles driven)

MPGc = 0.9755 (based on 36 gallons burned and actual average mpg of 22.5 - Trip 1 meter overestimates the MPG - surprise!)

MPG65 = 27.4 Calculated from 3 x 10 mile tests (5 miles each way) with values 27.8, 28.1, 28.2. Took the median (28.1 x 0.9755 = 27.4 mpg.

 

[blankman]

Any issues with the car along the way? I have yet to take mine on an extended road trip but want to in the future.

No issues at all. Drove it from Tampa to sarasota, parked it for a week then flew back down to drive it home. Well I say no issues other then the ungodly pypes muffler delete on the car. Got that sorted with a borla s type cat back 2 weeks after I got home. I was more amazed at the mileage I got coming back up north.

 

[Paddles]

Any issues with the car along the way? I have yet to take mine on an extended road trip but want to in the future.

You have to try it man, these cars are amazing road trip cars. Take it to a shop for a road trip inspection if you need peace of mind but generally if you keep up with maintenance these cars won't leave you stranded in their stock form. I've already taken mine to 11 states and counting

 

[Sean22]

You have to try it man, these cars are amazing road trip cars. Take it to a shop for a road trip inspection if you need peace of mind but generally if you keep up with maintenance these cars won't leave you stranded in their stock form. I've already taken mine to 11 states and counting

Will do!

 

[paulm1]

21 GT 6spd, 3.55 gear. If I keep my foot out of it (which is a big if) winter time I'll get about 21mpg, maybe a little more. This is 90% highway, 10% city in NE PA, the cold kills MPG here. Summer time approx 23-24mpg under the same conditions.

 

[LCK22GT]

22GT, 6 speed, 3.55, CAI w/ tune, 93 octane. The best I've gotten is 25mpg on a highway trip, steady 75 MPH. The worst I get is 15 driving around town and mashing the gas once in a while.

 

[Skye]

V8, MT, 3.55, 16 gal tank, primarily Sport+ Mode, mixed driving.

The tank at fill frequently reports 255 mi / 410 km, which comes to 16 MPG / 25 kmPG.

YMMV.

 

[DougS550]

i have a 2020 mustang gt and i only roughly get 170 to 180 miles from full tank.
i feel like this is too low. or is this normal?

I think I was averaging around 13 mpg on my last fill up last summer, E85.

 

[Crew4991]

It depends on how you drive and what kind of driving you do.

I have a manual and get about 27 mpg but most of my driving is done cruising on a freeway.

 

[Paddles]

V8, MT, 3.55, 16 gal tank, primarily Sport+ Mode, mixed driving.

The tank at fill frequently reports 255 mi / 410 km, which comes to 16 MPG / 25 kmPG.

YMMV.

I see what you did there haha

 

[JetGray_Mach1]

Getting 260 miles to the tank with full Aero on daily 6 speed Mach 1 (Sport +). You must be driving it aggressively, I am sure I hit single digits for mpgs when I drive her hard. Plus it all depends, I drive highway mostly with not too much traffic. In Traffic these V8s chug the fuel.

 

[TonyNJ]

GT500 is as thirsty as they come. Something is wrong with your car.

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