As the title says really - roofbox or very small trailer for best MPG? We do quite a bit of camping and since having the kids we have only been going fairly local to Devon and Dorset over the last few years. We now want to go up to Scotland again to the west coast and possibly over to France this year. Both journeys will be about 500 miles each way and was wondering about the fuel consumption?

I have a roofbox and roof rails already though I have not used them yet on the Octy. I also have a factory fit towbar but don't actually own a trailor though friends of ours do.

Speed is not really an issue as I usually cruise at around 65mph anyway (2k rpm on the tacho in 6th gear)

Any ideas?

Trailer would be best in your case, as a small one would sit happily in the turbulent zone behind your car, whereas a box would increase the frontal area (and therefore the drag) quite considerably. The rolling resistance from a small trailer would be hardly noticeable, and it would be easier to load, too.

Then again, we were still getting 40+ mpg from my Fabia with a box on when we went to Scotland last year, and we had no such scruples about adopting an optimal cruising speed!

If you go for the roof box, mount it as far back as you sensibly can - the more it overhangs the front the more it acts as a big scoop to catch air and slow you down or cause you to use more fuel. I found this our the hard way on my golf tdi - it cost 10mpg overhanging the windscreen, only 5mpg when further back.

Of course, the roof box will allow you cruise legally at 65mph, whereas even on the motorway the speed limit with a trailer is 60mph and you are forbidden from using the third lane on 3 lane motorways.

Unless you have a rear number plate the cost of a plate to allow you to tow the trailer behind you car is likely to be about the same as the saving of using the trailer over a 500 mile journey, if that!

Check out the relative ferry costs for a higher vehicle (i.e. with roof box) versus a trailer for your trip to France - this cost differential is likely to far exceed any differences in fuel consumption!

Speed in france is'nt an issue , if your trailer is 750kg or under there are no speed restriction , what applies to the car is the same for trailer

i wont put my roofbox far back, i mount it further forward, because i dont like the possibility of the front wheels having lift, id rather have worse mpg than the steering going light. might just be paranoia though.

plus with roof box u can do 70mph safely, with trailer you cant by law

Have a look at my thread:

http://briskoda.net/octavia-ii/combi-roofbox-solution/111668/

I reckon 15% for the roofbox - and the position of the box is dictated by the radio aerial - if you want to keep it on.

Cheers,

Les.

Hi

I have a roof box and a decent sized trailer for camping. Due to the slower sppeds when towing I still get above 40mpg - often close to 45mpg which is good.

With roofbox only at normal speedy speeds - about the same.

140BHP TDI if that helps

If you are thinking of going to France then I would recommend the roof box simply because it will be cheaper on the ferry. With a trailer you will be well over the usual 5m length and will have to pay extra.

We took a big sun awning (about the same size as a big roof box) over to France last year and the consumption dropped from usual 50ish mpg to about 47 (2.0 TDi Estate) so it didn't seem to make that much difference.