• This topic has 42 replies, 31 voices, and was last updated 4 years ago by benp1.
Viewing 40 posts - 1 through 40 (of 43 total)
  • Roof rack / mpg equation.
  • Premier Icon Kryton57
    Full Member

    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.

    🙂

    Premier Icon simon_g
    Full Member

    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.

    Premier Icon cookeaa
    Full Member

    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?

    Premier Icon wobbliscott
    Full Member

    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.

    Premier Icon Daffy
    Full Member

    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.

    Premier Icon cp
    Full Member

    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.

    Premier Icon garage-dweller
    Full Member

    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.

    Premier Icon cp
    Full Member

    Aero bars make a huuuuuuge diffference to noise.

    Premier Icon br
    Free Member

    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 🙂

    Premier Icon PeterPoddy
    Free Member

    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.
    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)

    Premier Icon MoreCashThanDash
    Full Member

    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.

    Premier Icon DickBarton
    Full Member

    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!).

    Premier Icon Kryton57
    Full Member

    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.

    Premier Icon scotroutes
    Full Member

    The effects will obviously be worse the faster you drive.

    Premier Icon richardkennerley
    Full Member

    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.

    Premier Icon thecaptain
    Free Member

    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.

    Premier Icon teasel
    Free Member

    the mess in there at the moment is making me sad

    WTF?!

    Tidy it, you slug!

    Premier Icon iainc
    Full Member

    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.

    Premier Icon freeagent
    Free Member

    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.

    Premier Icon cokie
    Free Member

    On my car

    On mix of B-A-M roads;
    Without: 45-50
    W. rack (unloaded): 40-43
    W. rack (loaded- 2 bikes): 35-37

    Longer A-M road stints;
    Without: 47-52
    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.

    Premier Icon oafishb
    Free Member

    Another thought…..
    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.
    But just a thought.

    Premier Icon smogmonster
    Full Member

    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.

    Premier Icon Kryton57
    Full Member

    Oh wow, the Sea suckers….

    How does the rear wheel stay on? Is there another sucker just for that?

    Premier Icon steve_b77
    Free Member

    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.

    Premier Icon molgrips
    Full Member

    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.

    Premier Icon Kryton57
    Full Member

    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.

    Premier Icon Kryton57
    Full Member

    Oh hold on. My mindulness manual says i shouldnt care about such things…

    Premier Icon sprinter2139
    Free Member

    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.

    Premier Icon gowerboy
    Full Member

    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.

    Premier Icon iainc
    Full Member

    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.

    Premier Icon steve_b77
    Free Member

    It does in a sporty kinda way, 1 series are erm, 1 series with other without roof bars

    Premier Icon newrobdob
    Free Member

    I think my roof rack might hurt my MPG.

    However I don’t track the MPG on this car unlike every other car I’ve owned (or my company Focus) as I’m just too scared to know the truth. 😯

    Premier Icon molgrips
    Full Member

    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.

    Premier Icon Kryton57
    Full Member

    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.

    Premier Icon wilburt
    Free Member

    After a year of taking them in and off I now leave them on.
    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.

    Premier Icon julians
    Full Member

    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 though

    Premier Icon nickc
    Full Member

    Wing bars and a carrier on my 125d 1 series, made no difference to noise or fuel economy. Look ok to my eyes

    Premier Icon PeterPoddy
    Free Member

    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. 🙂
    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.

    Premier Icon DickBarton
    Full Member

    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.

    Premier Icon Kryton57
    Full Member

    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.

Viewing 40 posts - 1 through 40 (of 43 total)

The topic ‘Roof rack / mpg equation.’ is closed to new replies.