Roof rack / mpg equation.
Is there one? Being tight and a) too lazy to stick a rack on the car every weekend or b) leave it there empty because I cruise the motorways for work I wondered if I should start using it more.
So if I normally get 55mpg average, what impact will it have to my mpg.
🙂Posted 4 years ago
I find the Thule wingbars (without bike carriers) are 1mpg at most. It’s much easier to slide a carrier (or two) on the bars when I need them, than it is to put on and remove the bars.Posted 4 years ago
Will you be driving any slower?
Are you factoring the cost of a roofrack/carriers Vs towbar/rack/light board electrics? Into any cost/benefit/MPG calc?Posted 4 years ago
Don’t waste your time worrying about it. I’m sure there is a theoretical difference but you won’t notice it. A lot less faff than removing all the time. I think I read in the handbook for a previous car that it was about a 4% reduction.Posted 4 years ago
It’ll depend upon the car’s aerodynamics, the position of the forward bar in relation to the curvature of the windscreen, the profile of the bars, if there’s a bike rack attached to it, etc.
What I can tell you is that when I had standard BMW bars on the roof of my Touring, I could hear them at anything over 40mph and could feel them at anything over 90. I now have Whispbars and can’t feel/hear them at all.Posted 4 years ago
I have two racks permanently attached to aero bars on the top of my legacy. Make absolutely no measurable difference to mpg compared to them not being there.
Bikes go on every now and then but it makes the process so much easier to just leave the racks on the car.Posted 4 years ago
Kryton I used to leave mine on.
Square bars, Mondeo before, Passat now.
They knock at least 2-3 mpg off if travelling at motorway speeds over any distance ime. If it’s rush hour crawling along they make a lot less difference.
It’s the rattling and whistling that gets me to take them off! But then I’m regularly spending a couple of hours slogging along the motorway at 70 on the way to a client site and I do use cheap, square bars. I also like it quiet (no radio etc.) when I am driving.Posted 4 years ago
Aero bars make a huuuuuuge diffference to noise.Posted 4 years ago
Years ago on a petrol Vectra they reduced my MPG from 33 to 30.
Company car and fuel, so no effort to save money nor go slow 🙂Posted 4 years ago
When I used to do a lot of miles for work, and I kept accurate fuel records (geek alert!) as I still do, it was fairly obvious that roof bars with 2 bike racks fitted cost 1-2mpg consistently.Posted 4 years ago
That was a diesel estate car.
I took them off, and as they were such a faff to refit we switched to a tow bar rack as they’re much more practical all round. (Eg height restrictions)
We kept our bars and bike holders on. 1-2mpg is bigger all compared to the faff of taking it all on and off. We switched to a tow bar rack on the new car for non-mpg reasons.Posted 4 years ago
I leave my bars on and have 3 racks…I didn’t notice a real difference when they were first fitted (actually I didn’t notice any real difference until about 8 months ago), I’m now seeing a 10mpg reduction (sadly keep track of mileage and fuel stops), but I think this is to do with other things – like perhaps a slightly heavier foot or not changing up as quickly as before. I think the bars and racks might have a 2mpg impact; with bikes on, it is much more, but having more than 1 frequently isn’t common; 2 now and again and 3 rarely – so the mpg drop isn’t quite as noticeable.
Don’t have space, time or interest in removing them and reinstalling them…so they stay on.
Strangely, I think they make the Fiesta look better than with a plain roof (although I may be falling victim to the ‘lifestyle choices’ mince there!).Posted 4 years ago
Intriguing. I think leaving them on my 120d would look crap, and the noise during a 5hr trip to Wales would unbearable.
I usually stick the bike in the boot, but the mess in there at the moment is making me sad. For the sake of it I might stick the bike on the roof on the way back from BOtB at Pembury, leaving it in the boot whilst clean on the way there to see the mpg difference.
I already have bars and rack so the cost of those doesn’t come into it.Posted 4 years ago
The effects will obviously be worse the faster you drive.Posted 4 years ago
Whispbars are fit and forget. I don’t see any difference in mpg and think they look fairly decent compared to standard roof bars, make no noise either.Posted 4 years ago
Rack itself isn’t a big deal, I certainly used to notice the effect of a tandem on top of a micra though, perhaps 2-3mpg.Posted 4 years ago
the mess in there at the moment is making me sad
Tidy it, you slug!Posted 4 years ago
Wingbars and 3 Thule 591’s atop my 5 Tourer for last 80K miles. I rarely drive over 75mph, and I do notice a slight noise from them above about 60. I have no idea what they do to fuel consumption but suspect not a lot in comparison to driving style impacts.Posted 4 years ago
slight drop in economy (2-3 MPG – yes, I do keep records as it is a company car) but noticeable noise at motorway speeds on my Passat.
They also made the Dartford Bridge in a crosswind even more exciting..
I tend to take them off now, but part of that is so I don’t advertise the fact I’m a bike owner to anyone driving past my house.Posted 4 years ago
On my car
On mix of B-A-M roads;
W. rack (unloaded): 40-43
W. rack (loaded- 2 bikes): 35-37
Longer A-M road stints;
W. rack (unloaded): 39-42
W. rack (loaded- 2 bikes): 34-38
Interestingly, there doesn’t seem to be a difference between 1 or 2 bikes on the roof, or different types of bike.Posted 4 years ago
Isn’t it just advertising ‘I have bikes in my garage/shed’ to thieves?
Two neighbours of mine on a very quiet street had theirs on their cars constantly, parked outside. Mysteriously, both sheds were broken into and bikes stolen.
Probably coincidence.Posted 4 years ago
But just a thought.
My Thule aerobars would easily knock 5mpg off my X1 if I left them on. And they were constantly bloody whistling… I was always a little paranoid aboiut the advertising to thieves that I have bikes somewhere as well. In the end I bought a Seasucker as its a doddle to remove and install, takes about a minute to put on, 5 seconds to remove.Posted 4 years ago
Oh wow, the Sea suckers….
How does the rear wheel stay on? Is there another sucker just for that?Posted 4 years ago
I’ve got wing bars and 2 carriers permanently mounted on my 320d M Sport tourer. Average from new over 38000 miles is 48.7mpg, make of that what you will.Posted 4 years ago
I take mine off. Although I don’t use them often.
They are Whispbars (isn’t that chocolate?) with the sticky out bits i.e. wider than the car, and they do make a noise at motorway speeds. It’s not loud, it’s just more wind noise. The bike holders make quite a bit of noise though.Posted 4 years ago
320d M Sport tourer.
Yes but likely as it is we have the same engine, your dar looks cool with them on, like a sports utility straight out of an austrian snow scene. My 120d on the other hand will look a bit
Shit.Posted 4 years ago
Oh hold on. My mindulness manual says i shouldnt care about such things…Posted 4 years ago
I’ve got Thule WingBars on my A4 and you can’t even hear them below 70-80mph. They howl like a werewolf even at 30mph if they have frozen water droplets on them from the night before though!
As for MPG, not even a measurable difference on the dashboard readout. 45mpg average before, 45mpg average afterwards.Posted 4 years ago
I find that leaving bars on makes an annoying noise and makes my fuel economy worse by up to 5mpg. So I take the bars off. Only takes a minute as I have roof rails. The feet have Allen key bolts holding them on. I use hex bit in a cordless drill to undo the bolts quickly.Posted 4 years ago
For those taking bars on and off, how frequently do you do this ? I have between 1 and 3 bikes on the roof at least once, usually twice, often 3 times a week and can’t imagine the extra faff time that it would take me to take the carrying system on and off. Wing bars, 3 x 591’s, estate with flush rails.Posted 4 years ago
It does in a sporty kinda way, 1 series are erm, 1 series with other without roof barsPosted 4 years ago
For those taking bars on and off, how frequently do you do this ?
Three, four times a year. Usually I use a towbar rack when driving to ride but I rarely do that. I ride from home.Posted 4 years ago
steve_b77 – Member
It does in a sporty kinda way, 1 series are erm, 1 series with other without roof bars
I’m quite offended, my 1 series – an F20 – looks pretty good (without roof bars) unlike the old one.
Posted 4 years ago
After a year of taking them in and off I now leave them on.Posted 4 years ago
There is a hit on mpg on the long runs but I still 60mpg on my last trip up north and also its a bit noisier but this is outweighed by the benefit of them being fitted when needed, not getting damaged in storage and making it easier to find the car.
I have an f20 1 series (m135i) and leave thule aerobars plus 591 rack on all the time.
At motorway speed there is about a 3mpg reduction, can’t tell what the reduction is for non motorways.
The noise is significant thoughPosted 4 years ago
Wing bars and a carrier on my 125d 1 series, made no difference to noise or fuel economy. Look ok to my eyesPosted 4 years ago
I thought of this thread yesterday – I was on the M3 at a steady 70 and a Nissan Cashcow came past doing maybe 85 and the whistle from his roof rack was clearly audible from 2 lanes away, over my engine, with me wearing earplugs! It must have been HELL in the car. 🙂Posted 4 years ago
I heard him approach, and I could still hear him when he was 2-300yards away. I reckon he was rushing to get to the 40mph restrictions to save his sanity.
I can’t say the wind noise bothers me that much…no whistle but I think there is an increase in background noise…always have volume set at ’10’ (out of 30 – 11 should be done but it messes with my preference of a ‘balance’ for volume)…so I can’t say the wind noise is a distraction.
Square bars, fitting kit and racks all by Thule.Posted 4 years ago
Wing bars and a carrier on my 125d 1 series, made no difference to noise or fuel economy. Look ok to my eyes
I think i posted here about a year ago, when a round trip to Peaslake with my bike on the roof had shocked me at 55mpg. Maybe the torque and turbo engineering in these modern diesels overcomes the extra drag a bit.Posted 4 years ago
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