Roof Box and fuel economy

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Wed 10 Oct 2007 20:54
Roof Box and fuel economy - ma
I am of to the Alps in December and may need a roof box on the car. Does any one have any experiance of how much the fuel economy will reduce by?. The car is a 1.8t Passat estate that generally returns around 35-36 mpg on a fast motorway cruise. The roof box is a long thin one as opposed to the squarer bulky ones.

Thanks
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Wed 10 Oct 2007 21:09
Roof Box and fuel economy - Stargazer {P}
Matt,

Passat estate (2005) 1.9 TDi 130 with long thin streamlined roofbox (Thule Atlantis 780) on roofbars/rails. No roofbox 53mpg on long runs (can be 50 or 57 depending on traffic and weight of right foot) and about 2-3mph less with the roofbox, can be upto 6mpg worse if a lot of headwinds.

hth

StarGazer
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Wed 10 Oct 2007 23:02
Roof Box and fuel economy - ma
excellent less than i'd hoped!

thanks
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Thu 11 Oct 2007 12:18
Roof Box and fuel economy - horatio
About 4 - 5 mpg
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Thu 11 Oct 2007 14:04
Roof Box and fuel economy - Cliff Pope
It surely depends on speed? Negligible effect at low speed, considerable at high speed.
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Thu 11 Oct 2007 15:06
Roof Box and fuel economy - Stargazer {P}
Cliff,

Yes it does depend on speed, since the OP was interested in a long fast motorway cruise I only gave the figures for this type of driving. I tend not to do local driving with the roofbox in place (when it would be empty) but on the few occasions that it has been left in place then <2mpg reduction in economy, 2-3mpg reduction for steady 60mph (average for motorway and dual carriageway) and 4-6mpg reduction if pressing on or strong headwinds.

I thought that it was of more use to the OP that it was an identical shaped car with a similar shaped roofbox.

regards

StarGazer
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Thu 11 Oct 2007 15:19
Roof Box and fuel economy - smallfish
I find that I definitely drive slower with the box on which helps economy - tend to use it in the summer only so other factors like traffic jams on the M5 make accuracy of with/without comparison a bit unscientific.
Overall fuel consumption is not too different - on a run I get 31-34mpg with the box vs 33-35mpg without it in a Seat Leon 1.8t .
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Fri 12 Oct 2007 10:22
Roof Box and fuel economy - barchettaman
I did my record lowest ever fuel economy in the Astra with a roof box on (and a fullish load). Think it was 23mpg, but that was a stupidly fast run from Dusseldorf to Calais to get the last ferry.
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Fri 12 Oct 2007 10:27
Roof Box and fuel economy - BobbyG
Not the same, but when I had 4 bikes on roof of car, economy dropped by nearly 10mpg!
--
2007 Seat Altea XL 2.0 TDI (140) Stylance
2005 Skoda Fabia vrS
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Fri 12 Oct 2007 11:06
Roof Box and fuel economy - horatio
Be sure to report back and let us know what result you actually get.
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Fri 12 Oct 2007 12:27
Roof Box and fuel economy - ma
Will do, thanks to all posters it wasn't as bad I was expecting


matt
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Tue 16 Oct 2007 14:34
Roof Box and fuel economy - ijws15
Used to lose about 4-5 mpg in the 1.8 T Saloon. Not all down to the box, some would be due to four people in the car and the boot full as well!

Check the instructions about maximum speed - mine states 60mph max (it has seen 90 but I did get nervous).
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