Roof boxes and fuel economy

MX5huggy

Driven to the Alps twice in the same BMW X3 once in winter so no aircon but with a roof box (full of skis etc) & 4 adults 22mpg, summer so air con on but no roof box, 2 adults 26mpg. It a 3l petrol BTW.

forgotmyname

Ebay bargains sometimes, Got mine for £40 because it was a little village out in the sticks.
But i lost out on a which few sold for more than i was willing to pay.

Sometimes they can be as much as a new one.

Ebe_Scrooge

We've got a very big roof-box, pretty much the biggest one available. We travel from Scotland to the South coast a couple of times a year visiting family and friends - it's a 500 mile trip ( each way ), almost exclusively motorway miles. We notice a huge difference when the roof box is on - we can do the trip in about 1 3/4 tankfuls without the box, it's about 2 1/4 with the box on. So I would estimate a good 1/2 a tankful difference on that trip.

Having said that, the convenience of the roofbox is brilliant, I wouldn't be without it, wouldn't be able to transport a family of 5 for 2 - 3 weeks away without it.

I must admit, given the extra cost of the fuel I have thought about a trailer instead. No idea how that would compare in terms of fuel usage, and it's the hassle of having to get a towbar fitted etc., I may look into it one day .....

But anyway, that's my take on your original question :-)

sunshinetours

If towing you are limited to 60 on motorways and can't use third lane so it would change possibly the dynamic of your whole trip. Roofbox will increase drag but no reductions in speed legally required

Roofboxes are great and roofbox.co.uk is a great site. Bought our 420 litre Farad one from there a few years ago and very knowledgable people on other end of phone if needed and pretty good prices. The "hoist" is as LandyAndy suggests and no use to me. If going for a full width one then double sided opening is a useful feature.

As others have suggested search on ebay or locally or buy one and sell it on afterwards if not required

vikingaero

I get a 10-15% hit in economy with the roofbox on our MPV. But that's mainly high speed driving.

I think it will depend on the type of car you have. A large roofbox will make more of a dent in MPG on a small car than when fitted on a heavy brick-like 4x4 which has poor MPG in the first place.

Gloomendoom

vikingaero wrote: »

I get a 10-15% hit in economy with the roofbox on our MPV. But that's mainly high speed driving.

I think it will depend on the type of car you have. A large roofbox will make more of a dent in MPG on a small car than when fitted on a heavy brick-like 4x4 which has poor MPG in the first place.

Yup. The biggest factor governing the extra consumption is the percentage increase in total frontal area when you add the roof box (and how fast you drive.) The extra weight won't help either.

AdrianHi

Thule Atlantis 780 (480 litres) roofbox. It is quite streamline. On a long trip at mostly 70mph along with extra load weight it seems to increase fuel consumption by about 2mpg. 53/54mpg down from 55/56mpg on the same trip. Not really a concern, we leave it fitted throughout the holiday. A trailer will cost you in mpg too due to rolling resistance of an extra pair of wheels.
I suspect the roof rack increase in mpg reputation comes from the days people loaded luggage onto a rack and then secured it with bungees and tarpaulin. Not very aerodynamic.
We also bought 1 x Thule 571 Roof Box Lift & Storage System (TH571) - a hoist. I did have to buy some heavier duty raw plugs and screws that those supplied but it is excellent and allows me to fit the roof box on the car by myself in under 5 minutes. Watch out for height clearance through the garage door. Our next car due June/July is too tall so we'll have to lift it out of the hoist and mount it by hand - it will be a 1 man and 1 woman job.

whibs897

I am a keen skier and went to the Alps over Christmas, we invited my brother to join us and he purchased a streamlined Thule skibox from skibox dot co dot uk. I know that i do use more fuel on the long haul but my brother said his fuel consumption hardly changed.

If you are going to buy a roof box or skibox and you want to use it regularly then pay the extra for a streamlined box. Over time the savings will make it worth while:beer:

If you are a once a year roof box traveller then grab your self a Halfords roof box. I did find the skibox.co.uk turned out cheaper than the roofbox company mentioned.

Flyboy152

Kilty wrote: »

Also - opinions on brands etc?

www.roofbox.co.uk will do me a "Karrite" 320L box with "CRUZ" bars for £140

You can't go wrong with a Thule.

Flyboy152

Kilty wrote: »

Storage might be a problem....... but I've noticed that roofbox.co.uk give you a free "hoist" with it which will allow you to store it in the ceiling of a garage - don't know how well that works

Especially if you don't have a garage.