Mud Flaps and MPG - delboy100

I was wondering if anyone has ever experimented to quantify the effect of mud flaps on fuel consumption.

One would assume they incur added wind resistance and thereby reduce fuel economy? Granted this may depend on the design of the mud flap but is the effect theoretical/negligible or 'real'?

Mud Flaps and MPG - Cliff Pope
Good question.
It might also depend on whether they were actually flapping mud or water, or just dangling in the slipstream.
Maybe there is a turbulence effect caused by their proximity to the revolving wheel - they might even reduce air resistance by containing this.
And then there is the full-width kind that coaches have.
Mud Flaps and MPG - Beesmart
Hi, Delboy 100
When volvo bought their 3series out they all had mud flaps on, but due to the fuel economy, they took all flaps off unless the customer asked for them.
Mud Flaps and MPG - patpending
When volvo bought their 3series out they all had mud
flaps on, but due to the fuel economy, they took all
flaps off unless the customer asked for them.

well Beesmart I bought such a Volvo and used the mudflaps as a last minute wish just before closing the deal, the dealer tried the fuel consumption argument on but I got my four fitted flaps, they were really the icing on the cake and made my Volvo look rally nice!

I fitted an original set on a BMW 3 series myself. As a layman it took me all afternoon (each one was slightly different), though having learnt how it worked , the same procedure on a second 3series would only have taken me an hour...

so I would say always go for mudflaps, they add to the car's appearance, save the paintwork and reduce spray for other users. just get someone else to put them on!

Mud Flaps and MPG - John S

Any add-ons will have an effect on fuel consumption, although the contribution of each individual item may be small. I suspect it may be difficult to relaibly measure the effect of normal mud flaps outside a wind tunnel, but it will be there. I seem to recall that Austin-Rover deleted the mudflaps on the Metro HLE which was the 'fuel economy special' of the range on the grounds they affected fuel consumption.


John S
Mud Flaps and MPG - M.M
Do you remember the first really modern Audi 100? Can't remember the year but perhaps around 1984?

These were some of the first mainstream large saloons which were designed with minimum drag in mind, didn't they have the 0.30 drag figure logo'd in the rear quarter window?

Anyway I understand the only model that actually matched this figure was the base 1.8 with narrow wheels/tyres. The 2.2 luxury models had a larger drag figure due to the wider tyres.

Or was I dreaming??

Mud Flaps and MPG - Baskerville
No you're right. I remember that sticker because I used to get a lift to school in one with a friend's dad on bad weather days and it used to break down quite a bit so we had to push it. Weren't they the first to have flush-fitting glass with no external window surrounds? I don't remember all this making it easier to push, mind.
Drag - M.M

You were obviously pushing it much too slowly!

Mud Flaps and MPG - J Bonington Jagworth
"..the first mainstream large saloons which were designed with minimum drag in mind"

Assuming you'd regard it as mainstream, the Citroen CX had a similar drag coefficient to the Audi 10 years earlier. In practice, it was much better, because the suspension always remained level, so it did what is said on the tin, as it were!

However, your point about the effect of wider tyres and accessories is certainly true - the much faster be-spoilered and wide-wheeled CX turbo had a lot more drag.

Come to think of it, the even earlier NSU RO80 was designed for low wind resistance, too - no doubt where Audi got the idea...
Audi 100 & Citroen CX. - M.M

Hmm...well the CX was mainstream in our household but not exactly your average car. I remember taking ours into the wilds of Herefordshire 20yrs ago and one old boy (Viva owner) asking if it had anything to do with Concorde.

Sadly I'm not that sure the CX had such a good CD figure...the publicity led us to think it but the figures I suspect were a great deal worse than the Audi 100. I know they were for the later Turbo's anywy.

I'm sure the Audi 100 1.8 was the first to hit the magic 0.30.

That Audi was a staggering car. In 2.2CD form it was large, had a superb ride/refinement, could do 120mph yet driven carefully could stretch 35 mpg plus....and no rust. It really was the first of the type of capable modern vehicle we have now.

Audi 100 & Citroen CX. - J Bonington Jagworth
MM, I suspect you're right about the magic 0.30 figure. The only figure I can find for the CX is for the later turbo version, which was not so good.

As for "the first of the type of capable modern vehicle we have now" (the Audi) I find it hard to disagree. I have a 13-year old model 90 which, like the 100, has the flushest of glass and, unlike a CX, no rust!
Mud Flaps and MPG - mal
Lets not forget mudflaps reduce the damage to your paintwork especially the bottoms of the doors and sills.
They also reduce the spray in wet weather increasing visibility for the following traffic.
Personaly I would never be without them and accept the negligible increase they must have on fuel consumption, and the detrimental effect they have on the look of the car.
Mud Flaps and MPG - delboy100
I'd do the test myself if it weren't for the fact that attaching my rear mud flaps is a fairly lengthy process.

Ultimately, I would imagine the effect is pretty small?

I know opinions differ but I do think mud flaps do protect the sides of the cars paintwork from dirt/debris thrown up by the wheels so I think I'll keep them on whatever.

Mud Flaps and MPG - Beesmart
Hi. I wish they would make flaps for the rear of my car, which is a smart. B ut i believe you have to modify flaps off an A- series M/B. At least it would save the car behind getting all the rubbish of my wheels, and also keep my rear window alot cleaner.


Value my car