Decreased mpg due to mud guards? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Madara · 12-26-2016, 08:30 PM

Hey guys Ft86club community. I recently bought a 2014 Asphalt FRS about 2 weeks ago

. Really excited about the car! I do have a question though(topic title). Is that possible? I haven't really noticed a difference yet since I haven't driven the car in the highway with them installed but just an idea... I just recently installed them as well.(OEM)

ryoma · 12-26-2016, 09:22 PM

doubt it. your driving habits will affect MPG the most

Jajanken86 · 12-26-2016, 09:56 PM

The OEM ones are pretty skinny and work well with the stock wheels. The wide rally armor flaps are more likely to cause significant drag. But idk how much more likely.

Sent from my SAMSUNG-SM-G935A using Tapatalk

FX86 · 12-27-2016, 12:19 PM

what color are they?

D_Thissen · 12-27-2016, 12:38 PM

You're joking.. Right?

new2subaru · 12-27-2016, 12:44 PM

Just add some of these and you'll even out.

8RZ · 12-27-2016, 12:48 PM

Drill some speed holes in the mudflaps for IMPROVED MPGs.

JD001 · 12-27-2016, 01:43 PM

Quote:

Originally Posted by 8RZ

Drill some speed holes in the mudflaps for IMPROVED MPGs.

Speed holes?? Is this like a vortex cyclone device that creates a vacuum on the attacking face thus sucking air through creating rush on back face that aids drag reduction and gives a positive airflow pattern that helps to self clean the car?

8RZ · 12-27-2016, 02:05 PM

Quote:

Originally Posted by JD001

Speed holes?? Is this like a vortex cyclone device that creates a vacuum on the attacking face thus sucking air through creating rush on back face that aids drag reduction and gives a positive airflow pattern that helps to self clean the car?

Precisely!

geezerbrzeezer · 12-27-2016, 02:39 PM

From the manual:

"After the installation of OEM mud flaps, three important steps must be taken:

1 - decrease the normally recommended tire pressure in each tire by 20 psi so that the reduced tire/wheel weight and (lowered vehicle) drag reduction will offset the mud flap drag effect on mpg numbers;

2 - increase the normally recommended tire pressure in each tire by 20 psi so that the reduced rolling resistance will offset the mud flap drag and tire pressure reduction instructions (in step 1 above) effect on mpg numbers;

3 - shine a flashlight into your left ear - a beam visible from your right ear means you're on empty - contact your dealer."

Madara · 12-28-2016, 03:32 AM

Thanks guys for some feedback. As for the the others commenters I've heard mud flaps decrease mpg due to having more drag. I was only curious and asking a legitimate question. Thanks though.

churchx · 12-28-2016, 04:23 AM

They may decrease slightly at highway speeds. I don't think you should care though, after all, you install them to protect paint, so probably that is of more importance then slight MPG drop, right? Also IIRC USDM fr-s-es might lack plastic underside body panels. If you care about MPG that much, you may consider retrofitting those to reduce drag.

8RZ · 12-28-2016, 08:06 AM

Hopefully my shark fin antenna drastically improves my MPGs.

churchx · 12-28-2016, 08:26 AM

All of those parts, antenna, sidemirrors, underpanels change drag by little. "Drastically"? If only by placebo feel. Though if they all are changed, cumulative difference probably will be noticeable enough (guesstimate combo of all those to be worth some .. 2-3mpg? And then again putting on stickier tires or big GT wing will make those efforts naught again

).

12-26-2016, 08:30 PM	#1
Madara Member Join Date: Dec 2016 Drives: 2014 Asphalt FRS Location: California Posts: 45 Thanks: 4 Thanked 1 Time in 1 Post Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Decreased mpg due to mud guards? Hey guys Ft86club community. I recently bought a 2014 Asphalt FRS about 2 weeks ago . Really excited about the car! I do have a question though(topic title). Is that possible? I haven't really noticed a difference yet since I haven't driven the car in the highway with them installed but just an idea... I just recently installed them as well.(OEM)

12-26-2016, 09:22 PM	#2
ryoma Senior Member Join Date: Mar 2015 Drives: 2015 Subaru BRZ Limited CWP Location: SoCal Posts: 1,561 Thanks: 34 Thanked 669 Times in 469 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	doubt it. your driving habits will affect MPG the most __________________ My 2015 CWP BRZ Build

12-27-2016, 12:38 PM	#5
D_Thissen Senior Member Join Date: Jan 2014 Drives: '13 Argento FR-S (Sold) Location: Ontario Posts: 2,126 Thanks: 3,209 Thanked 1,439 Times in 855 Posts Mentioned: 19 Post(s) Tagged: 2 Thread(s)	You're joking.. Right? __________________ My FR-S Build IG: dthissen

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12-26-2016, 09:56 PM	#3
Jajanken86 Senior Member Join Date: Apr 2016 Drives: Silver FR-S Location: Saipan ✈ Portland Posts: 231 Thanks: 92 Thanked 36 Times in 28 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	The OEM ones are pretty skinny and work well with the stock wheels. The wide rally armor flaps are more likely to cause significant drag. But idk how much more likely. Sent from my SAMSUNG-SM-G935A using Tapatalk

12-27-2016, 12:19 PM	#4
FX86 Banned Join Date: May 2016 Drives: on the wrongside of the road Location: rear floor mats Posts: 2,240 Thanks: 1,084 Thanked 2,087 Times in 1,015 Posts Mentioned: 14 Post(s) Tagged: 1 Thread(s)	what color are they?

12-27-2016, 12:44 PM	#6
new2subaru Weight Weenie Join Date: Aug 2015 Drives: 15 FR-S Location: Canada Posts: 2,586 Thanks: 5,016 Thanked 2,330 Times in 1,346 Posts Mentioned: 12 Post(s) Tagged: 0 Thread(s)	Just add some of these and you'll even out.

12-27-2016, 02:39 PM	#10
geezerbrzeezer Geezer Join Date: Feb 2016 Drives: 2016 Subaru BRZ Sport Tech Location: Ontario Canada Posts: 276 Thanks: 133 Thanked 190 Times in 111 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	From the manual: "After the installation of OEM mud flaps, three important steps must be taken: 1 - decrease the normally recommended tire pressure in each tire by 20 psi so that the reduced tire/wheel weight and (lowered vehicle) drag reduction will offset the mud flap drag effect on mpg numbers; 2 - increase the normally recommended tire pressure in each tire by 20 psi so that the reduced rolling resistance will offset the mud flap drag and tire pressure reduction instructions (in step 1 above) effect on mpg numbers; 3 - shine a flashlight into your left ear - a beam visible from your right ear means you're on empty - contact your dealer."

12-28-2016, 03:32 AM	#11
Madara Member Join Date: Dec 2016 Drives: 2014 Asphalt FRS Location: California Posts: 45 Thanks: 4 Thanked 1 Time in 1 Post Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Thanks guys for some feedback. As for the the others commenters I've heard mud flaps decrease mpg due to having more drag. I was only curious and asking a legitimate question. Thanks though.

12-28-2016, 04:23 AM	#12
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,333 Thanks: 696 Thanked 2,085 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	They may decrease slightly at highway speeds. I don't think you should care though, after all, you install them to protect paint, so probably that is of more importance then slight MPG drop, right? Also IIRC USDM fr-s-es might lack plastic underside body panels. If you care about MPG that much, you may consider retrofitting those to reduce drag.

12-28-2016, 08:26 AM	#14
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,333 Thanks: 696 Thanked 2,085 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	All of those parts, antenna, sidemirrors, underpanels change drag by little. "Drastically"? If only by placebo feel. Though if they all are changed, cumulative difference probably will be noticeable enough (guesstimate combo of all those to be worth some .. 2-3mpg? And then again putting on stickier tires or big GT wing will make those efforts naught again ).

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