Squeezing a few more mpg out of a mustang gt

[gk_ghig14]

I apologize if this is in the wrong section

I'm attempting to squeeze out a few more mpg from my 2014 mustang gt. I know it sounds weird but coming from 2 trucks, my mind can't comprehend getting less than 320ish miles a tank. Currently I'm getting between 17 and 19 mpg but would like 21 mpg minimum(16 gallon tank)

What I have done so far:
1. Lighter wheels. Dropped about 12-20 pounds rotational mass however the back wheels and tires are now wider(planning on ordering smaller back wheels)
2. Limited my top speed to 80 with the ford my key(speed limits are 75 so no going 55-60 here)
3. Tried 93 octane instead of 87(noticed no difference)

What I am considering doing:
Front splitter
Partial underbelly tray
Grill overlays(cover up the fog lights slightly)
Lowering springs

Any tips or other suggestions as far as my plans go?

[jeff88]

Welcome to EM! When you get to 5 posts, post up some pics of your beautiful pony!

"Changing the nut behind the wheel" is the first thing people here always say. If the speed limit is 75 don't do 80, do 75 or better yet 70 (obviously in the slow lane, don't get yourself killed ). Time the lights, so you don't rush up to a red, lot's of other things. Check out the Hypermiling Tips: 100+ Hypermiling Tips.

Those mods you are considering are good. I would do a belly pan (least noticeable, which I would assume you want on your Mustang) with a rear diffuser on the back side (very race-ready). If you do a splitter, I would make sure the grill is blocked as best as possible, otherwise you're moving air for nothing. Depending on how "stock" you want it to look you could use fiberglass, but I would recommend cardboard and/or cloroplast at least for testing purposes. Check out this page as well: 65+ Efficiency Mods

I can see why you got no improvement in MPG for the higher octane fuel. Unless your engine requires it, nothing changes to the FE. Higher octane doesn't mean higher energy content.

Good luck and have fun!

[euromodder]

Originally Posted by gk_ghig14

1. Lighter wheels. Dropped about 12-20 pounds rotational mass however the back wheels and tires are now wider(planning on ordering smaller back wheels)

Those are expensive mods for rather little gains in mpg.
They help, but they'll never pay for themselves in fuel saved.

I'm spotting the racer-approach to reducing fuel consumption.
No offence meant by that - we see it more often when folks join up.
The mindset that you need hi-tech mods to improve certain aspects of a car.
Well, as it turns out, you don't always need that.

3. Tried 93 octane instead of 87(noticed no difference)

There's little difference with higher octane or premium gas unless your engine is set up for it. And even then, it's marginal.
Once again, the fuel saved by "premium" gas - if any - won't ever offset the price difference.

Lowering springs

Another mod that's expensive for little gains.
Do it when you want to drop the car anyway, but not specifically to get spectacular better mileage.

Any tips or other suggestions as far as my plans go?

I'd look into changes to your driving style, rather than technical modifications to the Mustang.

Have a look what you could change :
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

Try to get the same average speed with a lower top speed.
The endurance racing mindset.
Smoother yet faster.

Stealthy mods like a grill block (can be done on the inside), air dam or even belly pan (bit more involved to build) are always options if you want to keep the looks of the car unspoilt.


Another option to consider is reserving the Mustang for the fun rides, and get a cheap-ish but far more efficient car for the boring rides.
If you do a lot of miles, the beater can end up paying for itself.

(It's a rather specific situation, but my new car will pay for itself in like 10 years in reduced fuel costs.)

[gk_ghig14]

Originally Posted by jeff88

Welcome to EM! When you get to 5 posts, post up some pics of your beautiful pony!

"Changing the nut behind the wheel" is the first thing people here always say. If the speed limit is 75 don't do 80, do 75 or better yet 70 (obviously in the slow lane, don't get yourself killed ). Time the lights, so you don't rush up to a red, lot's of other things. Check out the Hypermiling Tips:

Those mods you are considering are good. I would do a belly pan (least noticeable, which I would assume you want on your Mustang) with a rear diffuser on the back side (very race-ready). If you do a splitter, I would make sure the grill is blocked as best as possible, otherwise you're moving air for nothing. Depending on how "stock" you want it to look you could use fiberglass, but I would recommend cardboard and/or cloroplast at least for testing purposes. Check out this page as well:

I can see why you got no improvement in MPG for the higher octane fuel. Unless your engine requires it, nothing changes to the FE. Higher octane doesn't mean higher energy content.

Good luck and have fun!

Oh I'll definitely post pics. Especially to help visualize my ideas with stuff

As far as the speed thing, I posted that since I figured some people when they saw mustang would picture 90-100 going down the highway. Gotta cover my bases

I really wanna do the belly pan just gotta figure out how with the way the exhaust is(2 pipes all the way through). But I think with it being a mustang I can use some racing examples

The splitter I figured with help with downforce(yeah I'm a racer poser lol) but could also help with dropping the front end some, along with giving somewhere to mount an air dam more conspicuously. Would also allow me to mount something to even the front with the front tires(think that was one of the aero mods I read for mpg somewhere)

Which grille should I block? The bottom or the top, or both?

Ford says to run premium, as that's where their horsepower claims come from but regular is acceptable as long as the owner is fine with losing about 10-12 hp(which I'm perfectly fine with)

[jeff88]

Don't worry about getting flamed for speed. We will only suggest to slow down. In fact there are many racers on this site. One of my favorite build threads is Vekke's: VW Lupo 3L --> 2L. You might want to check out his thread for some inspiration.

If you do the splitter/air dam, it would definitely help with an attachment point for the belly pan. I would start the belly pan in the front for 4 reasons. 1st, you have a good place to have an attachment. 2nd, you will have better warm-up times. 3rd, you can figure out the exhaust issue later on. 4th, if you start in the back, you will end up with a parachute effect.

With regards to the exhaust, I don't think you have to worry about it too much. Many on here have just left their pan material a few inches away from the exhaust on either side. OEMs have started doing this too, take a look at the Audi a5 for an idea: Audi a5 Undercarriage.

Originally Posted by gk_ghig14

Would also allow me to mount something to even the front with the front tires(think that was one of the aero mods I read for mpg somewhere)

I'm not sure what you mean by this. Are you talking about making wheel spats? Wheel Spats

Originally Posted by gk_ghig14

Which grille should I block? The bottom or the top, or both?

Tough to say without seeing a pic of the front end. Most here say to block the upper grill. On my Corolla, I'm working on the bottom grill though, because the bottom is so big and the upper is so small, there isn't much gain in blocking in. My bottom grill is also inset, so my original block was also inset, gaining me nothing. If I push the block out to make the whole front bumper even, it will provide a much better benefit than the upper block (pure conjecture). Long story short, it depends. Only block both if you can get away with it cooling wise. You'll have to play with it. Maybe instead of doing 100% on one and nothing on the other, you can do 80% on both. Only how much fuel you pump at the gas station will tell you which option is best.

Does Ford say if you can run E85 or not? I'm not recommending it for fuel economy, but it does have a higher octane.

[gk_ghig14]

Originally Posted by euromodder

Those are expensive mods for rather little gains in mpg.
They help, but they'll never pay for themselves in fuel saved.

I'm spotting the racer-approach to reducing fuel consumption.
No offence meant by that - we see it more often when folks join up.
The mindset that you need hi-tech mods to improve certain aspects of a car.
Well, as it turns out, you don't always need that.


There's little difference with higher octane or premium gas unless your engine is set up for it. And even then, it's marginal.
Once again, the fuel saved by "premium" gas - if any - won't ever offset the price difference.


Another mod that's expensive for little gains.
Do it when you want to drop the car anyway, but not specifically to get spectacular better mileage.


I'd look into changes to your driving style, rather than technical modifications to the Mustang.

Have a look what you could change :
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

Try to get the same average speed with a lower top speed.
The endurance racing mindset.
Smoother yet faster.

Stealthy mods like a grill block (can be done on the inside), air dam or even belly pan (bit more involved to build) are always options if you want to keep the looks of the car unspoilt.


Another option to consider is reserving the Mustang for the fun rides, and get a cheap-ish but far more efficient car for the boring rides.
If you do a lot of miles, the beater can end up paying for itself.

(It's a rather specific situation, but my new car will pay for itself in like 10 years in reduced fuel costs.)

Wheels, I actually made a few bucks after selling the stock ones. Gotta love when a friend is getting rid of their car and dealer doesn't care what wheels is on it

Yeah definitely a racer approach to it, plus it looks good

I have considered a second car for daily driving but for the mileage I drive(1500ish miles a month) it would take a long time for fuel savings to pay off compared to just trying to squeeze out a few more mpg along with driving less

[gk_ghig14]

Well I figured out one major issue after looking at tip #1(drive less), according to google maps my commute(excluding lunch and weekend driving) should be 115 miles however I am filling up every 5-6 days(over double the miles),eek! Worst part is I don't ever recall driving that much. Time to start journalizing my driving in order to avoid this

However I still want to do eco mods that way along with less driving, I can achieve better mpg and possibly keep fuel costs under $100 a month(currently $290ish)

Now for pictures of possible eco mods and car:

Car as it sits now with the lighter wheels installed


Grille overlay(top is stock, bottom is with overlays). I think this will also give me a better attachment point for the grille block


Underbody of my car(car is a couple years older but same generation)


Splitter ideas

Factory boss chin splitter



Custom splitter with wheel splats(?)



Underbelly pan idea. Mind you this is on a car that goes 200+ mph and the installer said it cost near a grand and tons of man hours, mine will not be this elaborate

[gk_ghig14]

I also have a route question. There is a back road a couple miles from my house where I could easily cruise 50-55 mph however it is super hilly(well for Texas it's hilly) versus the highway which is relatively flat but 75 mph speed limit. The back road adds about 1-2 miles in overall length each day compared to highway. Which would be recommended for fuel economy?

[user removed]

If you can use the hills to pulse a glide and other traffic will not casue issues then your mileage would increase dramatically using the slower route.

regards
Mech

[chumly]

Originally Posted by gk_ghig14

I also have a route question. There is a back road a couple miles from my house where I could easily cruise 50-55 mph however it is super hilly(well for Texas it's hilly) versus the highway which is relatively flat but 75 mph speed limit. The back road adds about 1-2 miles in overall length each day compared to highway. Which would be recommended for fuel economy?

Try it for 1 tank and let us know the difference .Use the hills, they can help. Chumly