|
It surely depends on speed? Negligible effect at low speed, considerable at high speed.
|
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
|
|
|
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 .
|
|
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.
|
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
|
|
|
|
|
![2023 Skoda Kodiaq 2.0 TDI Sport Line 4x4 5dr DSG [7 Seat]](http://images.honestjohn.co.uk/imagecache/url/crop/90x60/https/cdn.uk.prod.group-mobility-trader.com/images/cas/52c6b8b97f04ab18823dd30425b1fa0f/934f9e8b265028802fd11a3042dfb677.jpg)
