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?
Never bothered to calculate the difference in fuel consumption but I notice
a lot more wind noise with them than without.
I would expect this increased drag to affect my fuel economy but I'm more
picky about the noise than anything. I remove them when not in use.
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.
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
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..
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