[shift_RUSH]

I recently installed OEM mudflaps...and also took a solo 460 mile roundtrip roadtrip last weekend. My fuel mileage was down at least 1.5 MPGs. Obviously lots of factors including wind/etc were possible variables. Granted, I took the interstate and set my cruise control ~81 MPH...but last year (same trip/route/speed) I was at least 1.5-2.0 MPG better, and this was with 2 folks (both 200 lbs each) and their gear.

In my nearly 2 years of reading/perusing here at CF, I seem to recall reading a comment or two about this being a possibility. Still, there are other CF'ers who achieve far greater fuel economy (than my rig) that have them installed.

My biggest hindrance to maximizing MPGs is my ARE TW Bedshell...though it was on for both this and last year's roadtrip.

I'm considering removing the back mudflaps, fwiw, to see if they play a possibly larger role in this scenario than the fronts. Plus, I see the front mudflaps having a greater impact on reducing rockchips overall.
Your comments/insights are appreciated.
TIA

 

[daveEM]

81 MPH? Yeah you drive too fast but you know that.

My 2013 came with little wind deflectors in front of the rear tires and of course the one going across the front under the bumper for the fronts. I suspect Nissan tossed the truck in a wind tunnel and did all sorts of fine tuning as to their size and shape to increase mileage.

I drove the truck home and like you a day or so later picked up four mud flaps for the truck. For sure like installing four 4x8 foot sheets of plywood. Oh well looks good and of course really not that bad.

Leave a little early and set the cruise control at 60 MPH. You will be astounded.

 

[FitzIngarage]

.... I'm considering removing the back mudflaps ... Plus, I see the front mudflaps having a greater impact on reducing rockchips overall. ...

I'd chose the splashguards and preserved paint (and therefore a rust free body) than the potential of better fuel economy. I agree with Dave, that chopping your speed will yield the best results.

 

[hyperduc]

I'd chose the splashguards and preserved paint (and therefore a rust free body) than the potential of better fuel economy. I agree with Dave, that chopping your speed will yield the best results.

Well, after all time is money and 81 vs 74mph is a 10% time savings. ::grin::

 

[shift_RUSH]

I'm more curious than astounded by this possible development of reduced fuel mileage. As a numbers guy, I find it all very interesting that the lil front OEM rear-wheel mudflap thingies help fuel economy...and that rear ones 'might' negatively affect the same. STILL, just too many variables to be scientific here.

Yep, am surely aware that driving slower yields better economy. A 3 hr trip jumps to 4 hrs just by driving 60 instead of 80. Nor do I want want to be that turkey driving so dang slow on an interstate. lol I had considered/intended to take rural hwys for this last roadtrip, but (and as usual for moi) the time savings won out in the end.

I'll be taking another ~350 mile roundtrip this weekend on the interstate. Will post back on Sunday.

 

[Clint]

Does safety figure into the speed anywhere here?
Those few minutes you shave off the ride can translate into a wreck, serious injuries or worse as there are many people on the road who drive like crap. I just had one cross 3 lanes in front of me with zero warning, had I been doing 80 as he almost took off my front fender there would have been a major wreck. I laid on the horn and he didn't flinch or acknowledge I was even there.
If you drive the way you describe why would you even care or give thought to fuel consumption, those flaps don't even come into play.

Clint

 

[shift_RUSH]

Will call this a Midwest vs East Coast:
Rural 2-lane hwys have more towns/cross traffic/intersections and therefore more opportunities for slower drivers merging/etc...
Interstates are generally what I consider far more of a no-brainer where the only slow downs are construction.

BUT, idiots are everywhere.

 

[Clint]

I hear you, I drive NJ to Florida and back at least six times a year but see many lame drivers on the interstate. Hopefully all your travels and mine are safe ones.

Clint

 

[hyperduc]

Does safety figure into the speed anywhere here?
Those few minutes you shave off the ride can translate into a wreck, serious injuries or worse as there are many people on the road who drive like crap. I just had one cross 3 lanes in front of me with zero warning, had I been doing 80 as he almost took off my front fender there would have been a major wreck. I laid on the horn and he didn't flinch or acknowledge I was even there.
If you drive the way you describe why would you even care or give thought to fuel consumption, those flaps don't even come into play.

Clint

Please not the safety argument. Or, stay in the right lane as to not hold up traffic.

There is no cross traffic on the interstate.

65mph has been in place for 30+ years. Cars are way better, way safer. We have disc brakes and new tire designs.
There are plenty of places in Texas with 85mph, Nevada with 75mph for cars AND big rigs, and the Autobahn in Germany, and the list goes on. None of these would be happening if there was a huge safety issue.

 

[Clint]

Depends where you live, way many around here refuse to keep right and that was the first motor vehicle law in this state. Keep right, pass left.
I was an EMT on a heavy rescue and recovery squad so I'm speaking with first hand memories.

Clint

 

[hyperduc]

There are more and more states with a "slower traffic keep right" law but they are not often enough enforced.

IMO having to pass on the right due to slow left hand drivers is pretty dangerous.

 

[shift_RUSH]

So...do mudflaps affect fuel economy? :nerd:

I would think that larger than OEM might/would have an even more negative effect.

 

[hyperduc]

I am running the fronts only because that seems to be the largest contributor to rock chips.

It seems like the fronts will have a small impact and the rear a slightly less small impact. I don't have any numbers to back that up, though.

 

[TruckIt]

Heading from California to Moab I went through a number of 80 MPH zones and most of it was 70-75 so depending on the limits where the OP was traveling, he may have been the slow one at 81.

 

[shift_RUSH]

Speed limit was 75...and my 81 felt about right. I was passed and did some passing of my own.
Guessing my 81 is closer to a 77-78 given inherent speedometer error.
While it was plenty warm, I didn't run my AC, fwiw. Cold/cool AC air always has me yawning w/in minutes. I'm a Summer guy through&through.

 

[Grommit]

Well, after all time is money and 81 vs 74mph is a 10% time savings. ::grin::

If your time really is worth that kind of money to you for that 10%, then you clearly earn so much that you don't give a crap about the cost of fuel. Just thought I'd throw that out there. ::wink::

 

[The other Sean]

I'm more curious than astounded by this possible development of reduced fuel mileage. As a numbers guy, I find it all very interesting that the lil front OEM rear-wheel mudflap thingies help fuel economy...and that rear ones 'might' negatively affect the same. STILL, just too many variables to be scientific here.

.

Something to do with the front of the tire being a large source of wind resistance for some reason. Look at most new cars and they now come with "spats" in front of all 4 wheels that don't look like much, but help deflect the air around the tire instead of in to or under it.

Mud flaps on the rear of the wheel well can act as a parachute. But, as those of us from northern parts of the country, the cost of paint dings and rust far outweighs a slight loss in MPG.

 

[rpcraft]

FWIW I found out tonight the economy drops off pretty fast if you go over 75. It used to be barely noticeable but with my old stock tires it was the difference being under 20 to over 21 MPG. Now that I put on the 285/75 tires its really noticeable when you are running an app like Torque or something that shows real time economy. I swapped to the new tires this weekend and I dropped to 17.9 just on one trip from Dallas to Houston (about 260 miles). At over 75 the average dropped so fast at one point I finally just slowed down to see at what point I could get it to start climbing again. I figured out about the max speed I can go and average around 18 MPG or more is 75, and the closer I stick to 70 the better.

The tires look great but its a kick in the nuts realizing I'll be losing about 70 miles or more per tank of gas. I didn't realize at the time I ordered the tires that 285/75-16 Falken Wildpeaks only come in an LT, which is much heavier than the non LT. -Guess I should have done a little more detective work. That being said I'll probably deal with it for a couple months and then get another set at the 265/75-16 size and make sure to get the non LT ones. I have a project truck (GMC Jimmy) that I will offload the 285's on to so it won't be a total loss.

That being said, as a guy who drives a lot, the difference between 75 to 80 isn't worth getting a ticket to me, especially when you compound the cost of increased insurance, combined with the drop off in economy. I average about 640 miles a week right now and saving 20 minutes on each leg of the trip isn't a huge deal to me, especially considering I usually stop mid way to get a soda and a snack. I also have driven across country several times and I'll admit on a trip like that 5 to 10 mph can save a lot of time but I figure if time savings was the gaol then I'd get a plane ticket.

 

[mtyler11]

I tend to be a bit precise when tracking things like mileage, not because I'm pinching pennies but because I want to see what effects different things have. The mini-fairings had a small (~.5mpg) impact when removed, the mudflaps had no discernable impact (less than .5) when removed (rock folded them like an accordian when offroad BUT didn't damage the fender) but the front fairing did have an impact... close to 1mpg. Not really believing it I fixed the front fairing up and attached it all and mileage came back up. So its up to you if loss of clearance is worth running the fairing (till you swap to a winch bumper), for me I'm better off with them removed (big chunk of ice made that decision for me initially) but I have 2 pr of generic flat flaps (look similar to RallyArmor) that will go on this weekend to protect the paint from the mud. They're much more flexible than OEM.

 

[RedDR]

You can put your tailgate down and that will get you better mileage.

LOL Not!

Just use the cruise control and maintain a decent speed. My truck gets better mileage if I use cc, no question about it.