Squeezing a few more mpg out of a mustang gt
 

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?

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 :turtle:). 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! :thumbup:

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. :cool:

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.)

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)

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.

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

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.

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

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
http://i1024.photobucket.com/albums/...ps00a59617.jpg

Grille overlay(top is stock, bottom is with overlays). I think this will also give me a better attachment point for the grille block
http://i1024.photobucket.com/albums/...ps96d5d308.jpg

Underbody of my car(car is a couple years older but same generation)
http://i1024.photobucket.com/albums/...ps10ce6147.jpg

Splitter ideas

Factory boss chin splitter
http://i1024.photobucket.com/albums/...psd439a1f9.jpg
http://i1024.photobucket.com/albums/...ps4ba97a19.jpg

Custom splitter with wheel splats(?)
http://i1024.photobucket.com/albums/...ps6be22929.jpg
http://i1024.photobucket.com/albums/...ps09829c39.jpg

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
http://i1024.photobucket.com/albums/...ps65c3fd6f.jpg
http://i1024.photobucket.com/albums/...ps23141c3c.jpg

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?

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

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

I second what has been said. I wouldn't add a splitter. 3.08 (or taller) gears would help at 75 if you don't have them. A mirror delete would be easy (and reversible) if your state allows them.

First off, what tire pressure are you running? It depends on your comfort level, but I'm guessing 40+ psi is your starting place. I could run 40 in South Carolina, but when I came back to Michigan I had to go down to 36 to keep from getting beat up on rough roads. Stiffer springs and lower profile tires will probably keep you from cranking up the psi too high.

I wouldn't put a grill blocker of any sort on in Texas until I could watch my coolant temp accurately. I've got the lower blocked off on my Mustang, but again this is Michigan.

Are you keeping engine rpm below 2000 rpm between shifts? 1500 rpm? My Mustang will pull in 5th (top) gear from idle (700 rpm). not quickly mind you, but for most driving it's fine. On the highway I am stuck running 2200-2500 rpm, but otherwise it's below 1500rpm. Well, except when I want to remind myself it's a Mustang... :D

Car has 3.15 gears, lowest numerical in the GT. Not sure on shifting rpm(it's an automatic). Cruising rpm are around 2000 if not a little more, tires are about 27.6" tall

Not sure on tire pressure either. I'll check after I get the car back from the shop however I'm gonna run as high as safely possible(probably around 40)

Edit: Max pressure for my tires is 51 psi

For reference, my cruising MPG vs speed is approximately:

55MPH - 38MPG
60MPH - 37MPG
65MPH - 35MPG
70MPG - 32MPG
75MPH - 29MPG
80MPH - 26MPG

I would recommend getting some instrumentation and finding your sweetspot.

Well took one of the backroads the other night and accidentally reset my mpg at a stoplight. But from that point on my speed was mainly 55-60 mph and I saw a high of 31 mpg but when home and parked it was reading 24ish mpg. Route had 2 stop signs, a stop light, and then a few street changes with acceleration needed

However this was at midnight so my real world results next month will very greatly. But gives me hope I can hit 21 at least on my daily commute


Mpg will also get better around february as the car will be getting smaller brake rotors(12.4" instead of 13.2", less unsprung weight) while allowing me to get smaller lighter wheels(17" at less than 20 lbs each hopefully). However this is mainly for cost savings, a good set of tires will run me $1300+ whereas new wheels and tires will cost me less(along with improving mpg)

Welcome !
I always get a kick out of " I HAVE to go 75... It's the speed limit"!
Had a poster claim he'd get run over in Dallas highway if he went 70!
Odd thing...I was I Dallas at the same time .... Never got run over or honked at!!!!
I drive sa to austin to Dallas to Tyler to abiene....Never had to go over 65...never.
1.)So....adjust the nut behind the wheel.
2.) get a gauge go where it's flat. Drive up and down at 50 55 60 65 70. Track your mpg at each now you KNOW what you mpg is at each speed
3.) raise psi to 42
4.) having duals doesn't stop u from having a pan see link in my post

I got 30+ mpg on a trip from Sacramento to Dallas in a 340hp, sub 6sec 0-60, 3890lb Q45 that can top out at 150mph. It was rated 22mpg highway. Avg 63mph and never went over 70mph.

You either want to get better mpg or you don't . 70% is how you drive.

Also it looks tight but the thing that helped me some was a 5.6% increase in overall tire diameter. If you decrease tire diameter you're toast. You can't reduce enough weight.

Yeah no way I'm going bigger tires. These are already massive(28")

Why not smaller though? I know on your car you can't change the computer calibration(I think) but on mine I can change all that for different tires

Well other than higher rpm cruising due to different effective gear ratio

Callerbration does nt change the rpm. Mpg is about lower rpm at cruise. Smaller diameter will increase rpm at cruise

Can you shift to N when the engine is running ? (check the towing instructions). If you can then P&G (Pulse and Glide) might be your newest friend depending on traffic. I'm using this just now on my first Auto and it has improved things a little - hopefully.

good post my mr A! I forgot all about this. I coast in neutral/engine ON all the time.....not on flat land but going downhill.
It did not work on a ford tarus I drove the rpms didn't drop when coasting in neutral.

The rolling hills at 55 MPH are probably a better bet.

Obviously different vehicles, but my Focus ALWAYS does better on rolling hills than on the flat. DFCO down, build up a bit of speed on the way down, then lose some on the way back up.

Also not going above 55 will help.

Another suggestion - review the "going at 75" decision.

If you need to use the flat and faster road at say 60-65 instead of the 55 side road then find a truck (as in SEMI) and follow it, then use P&G technique is illustrated here by Vekke very effectively over 2 videos.

Please feel free to film your trips and post a vid, that can sometimes generate more tips from others.

I can pulse and glide however it can be very "notchy" depending on the terrain and rpm. Seems to take a couple seconds for it to lock into drive.

Took coasting to an extreme just now, one road(rolling "hills") I coasted in neutral for a little over a mile and my lowest speed was 35ish(started between 55 and 60) then another road I coasted from about 60 till I was about 10 mph(this road seems to be mostly uphill after a small downhill). So depending on traffic levels during my commute(and time) I could possibly coast for a total of a couple miles

Happy new year!

The notchiness is normal, mine does that too.

On rolling hills you can also ride the terrain a little in gear - allow speed to build up on the downhills and carry that momentum on the next climb all in gear. Coasting is best when coming to a junction or riding a long descent.

That tapped of course you probably have more long straights that we do in North Britiain.

I love these threads on getting more mpg from muscle cars and big pickups. It's quite a challenge.
-One member recommended changing gear ratios in the rear axle. You can also accomplish that by mounting taller tires on the rear. It will introduce speedometer error. It worked well on one of my pickups.
-Changing driving habits is the cheapest mod. if you have a long daily commute, reducing speed could be a real bummer.

[quote[/U]wheelbender6;405152]i love these threads on getting more mpg from muscle cars and big pickups. It's quite a challenge.
-one member recommended changing gear ratios in the rear axle. You can also accomplish that by mounting taller tires on the rear.

Read post #17 then his response in #18

it will introduce speedometer error. It worked well on one of my pickups.
-changing driving habits is the cheapest mod. If you have a long daily commute, reducing speed could be a real bummer.[/quote]

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As far as gear ratio, I have 3.15 and the next tallest is 2.73 from a v6 mustang but gear changes are $500+ easy cause of labor

Tires, after hanging out with a buddy last night, found out technically I can go taller(as in I have wheel well space) but it may be tricky to find the tires. But I may look into it

Also dropped about 10 pounds off the front of the car(strut tower brace removed, sound tube removed, engine cover removed). Then I'll be dropping about 35 pounds off the rear when I take off the mufflers and install deletes

Just checked tire pressure all were at 40 but my driver front which was at 55(tires rated for 51) so I let air out until it got to about 40

Well found my next set of tires thanks to you guys. I will be going with 235/55/18 nitto 420s or 421q. While not a lrr tire or a true car tire, they weigh about the same as my current tires(31ish pounds), are narrower by 10-40 mm, bigger sidewall for more personal comfort, a few tenths of an inch taller for lower rpm, and I know how they handle(had them on my trucks) which means greater safety for me. Also since they are for 18" wheels I can easily cut down 5 pounds each wheel of rotational mass

One thing I like to do in a place I can't EOC (usually small hills, or hilly areas) is to accelerate down hill and ease off the throttle uphill- essentially driving to keep MPG. So on back roads I will be doing 57-59 (in a 55, 1400 RPMs seems to be her sweet spot in 6th gear), and I will ease off the throttle up a hill (speed down, keeping MPG at my target range), and accelerate down the hill (keeping my target MPG range). So I may be doing low 50s to 55 by the top of the hill, and up to 63, 64, at the bottom.

I have followed the whole thread, but don't remember anyone mentioning this. Regardless, it may not be the most successful way to do it, but it is better than just cruise control.

If you mostly drive on the highway or at least away from urban / suburban areas then weight loss is less crucial. That strut brace may also help you retain momentum on corners which can also help. If you want to lose the most weight then no spare and/or removing unused seats can save you more as can not running a full tank (although MPG is harder to work out running like this).

One tyre being out by so much - could that be another issue ? If mine were rated 51 I would run 45. Under-inflated tyres are more likely to fail than ones at the limit.

Just a thought how about doing a vid of your trip - nothing fancy, just mount a phone or a cheap £10 camera from ebay upload to youtube and we can see what you are facing. I put one on my thread here (Apologies for my poor music taste and it being winter here so dark).

For the grille block does it have to be on the outside or can it be on the back side of the grille?

The grill block is best on the outside, but some have reported minimal difference between inside and out. If you are going for that 'look', try out the backside and if it's not enough, then you can put one up front.

Outside is easier to remove if it causes cooling issues of any kind. Doubt it will but just in case.

:mad:If you look at the grille block in my sig link you will see a clear outside block.....
I did change to an inside block but cant find any pics:mad:

I used zip ties to pull it close to the grille.:thumbup:

Well looks like I may just do the outside grille block. An inside grille block would require removing my bumper and with my luck I'm sure it would get scratched or gouged.

Also ordered a tuner for my car which will allow me to fine tune the afr for better fuel economy and allow me to turn off the rear o2 sensors since I have deleted my cats

Whyvejukdvu delete cats?

Sound, weight loss, performance. Car is now louder(love), about 20 pounds lighter, and once I throw the tune on it'll have about 20 more hp for those occasional nights at the drag strip. Also I think freer flowing exhaust=better mpg

Picked up some new wheels and tires yesterday which dropped a few more pounds of rotational mass, and the new tires are larger in diameter and stated to have lrr technology by Yokohama. And due to the offset of the wheels, I'd say 98% of the wheel/tire combo is tucked in behind the body work

Also should be getting my vehicle specific tunes within the next 5 days, so I'll be installing the fuel economy tune in hopes of squeezing out 1-2 more mpg in combo with the new wheels and tires

Will also be doing a grille block. Zip ties are cheap enough that I can do it on the outside for Monday-Thursday then take it off for Friday night car meets