From another car type but maybe it applies:

With larger Jeeps like the Grand Larado it is suggested that the front rack
be placed in the forward slot and the rear in the back slot. If I recall
correctly, it was an economy (first) and noise (second) suggestion. This
was mentioned in the owners manual (1999 vintage). Of course when you buy a
Jeep now, the racks are not provided as standard equipment (rails yes, racks
no) 2002 vintage.

HTH, Glenn

"Robert" <rxobert.bxrown@txripnet.se> wrote in message
news:lRoQc.100099$dP1.345827@newsc.telia.net...
> Just for curiosity: Any of you with A4 Avant notice a worsening of fuel
> economy when driving with roof racks attached to the railings?
>
> Strangely enough I appear to burn 5-10% more fuel with them on, even if
> it's just the roof racks. Most of my driving is on the highway, avg
> speed approx 100 km/h (60 mph)
>
> Any of you notice a difference? Or is just my imagination?
>
> /Robert
>

 

Glenn Spence wrote:
> From another car type but maybe it applies:
>
> With larger Jeeps like the Grand Larado it is suggested that the front rack
> be placed in the forward slot and the rear in the back slot. If I recall
> correctly, it was an economy (first) and noise (second) suggestion.

Thanks Ken and Glenn. Good to hear that there may well be truth to my
theory that roof racks, apart from the wind noise, were causing me to
eat a bit more fuel. Didn't believe it at first when I went through my
logbook. . . . /Robert

 

Glenn Spence wrote:
> From another car type but maybe it applies:
>
> With larger Jeeps like the Grand Larado it is suggested that the front rack
> be placed in the forward slot and the rear in the back slot. If I recall
> correctly, it was an economy (first) and noise (second) suggestion.

Thanks Ken and Glenn. Good to hear that there may well be truth to my
theory that roof racks, apart from the wind noise, were causing me to
eat a bit more fuel. Didn't believe it at first when I went through my
logbook. . . . /Robert

 

"Robert" <rxobert.bxrown@txripnet.se> schreef in bericht
news:lRoQc.100099$dP1.345827@newsc.telia.net...
> Just for curiosity: Any of you with A4 Avant notice a worsening of fuel
> economy when driving with roof racks attached to the railings?
>
> Strangely enough I appear to burn 5-10% more fuel with them on, even if
> it's just the roof racks. Most of my driving is on the highway, avg
> speed approx 100 km/h (60 mph)

Why is it strange? The car-manufacturers spend a lot of time and money on
aerodynamics. Placing a horizontal bar (roof-rack) straight into the
wind-direction makes this aerodynamics dramatically worse. You should only
be carrying a roof-rack when really carrying something in it. Otherwise it
just adds noise and fuel-consumption..

Daniel

 

"Robert" <rxobert.bxrown@txripnet.se> schreef in bericht
news:lRoQc.100099$dP1.345827@newsc.telia.net...
> Just for curiosity: Any of you with A4 Avant notice a worsening of fuel
> economy when driving with roof racks attached to the railings?
>
> Strangely enough I appear to burn 5-10% more fuel with them on, even if
> it's just the roof racks. Most of my driving is on the highway, avg
> speed approx 100 km/h (60 mph)

Why is it strange? The car-manufacturers spend a lot of time and money on
aerodynamics. Placing a horizontal bar (roof-rack) straight into the
wind-direction makes this aerodynamics dramatically worse. You should only
be carrying a roof-rack when really carrying something in it. Otherwise it
just adds noise and fuel-consumption..

Daniel