Roof Rail Delete

[MINIz guy]

There have been reports that roof rails cause a lot of drag and hurt gas mileage. Yes, Roof Boxes And Ski Racks Really Do Cut MPG—More Than You Might Think

I remember reading stuff on Ecomodders, etc. I didn't have mine off for very long and I don't remember if I had any mileage increases with them off, though.

[OrangeFurious]

Originally Posted by MINIz guy

There have been reports that roof rails cause a lot of drag and hurt gas mileage. Yes, Roof Boxes And Ski Racks Really Do Cut MPG—More Than You Might Think

I remember reading stuff on Ecomodders, etc. I didn't have mine off for very long and I don't remember if I had any mileage increases with them off, though.

I get that. Removing the ski-rack had a distinct and immediate improvement in mileage (up 1.5-2MPG), comfort (noise) and drivability (at least subjectively it felt less wind prone).

[wpoll]

Originally Posted by MINIz guy

There have been reports that roof rails cause a lot of drag and hurt gas mileage. Yes, Roof Boxes And Ski Racks Really Do Cut MPG—More Than You Might Think

I remember reading stuff on Ecomodders, etc. I didn't have mine off for very long and I don't remember if I had any mileage increases with them off, though.

The OEM factory rails, mounted front to back (longitudinally) , are unlikely to have any measureable effect on fuel consumption or drag etc.

Mount some cross rails (laterally) on them and its a different story.....

[MINIz guy]

Originally Posted by wpoll

The OEM factory rails, mounted front to back (longitudinally) , are unlikely to have any measureable effect on fuel consumption or drag etc.

Mount some cross rails (laterally) on them and its a different story.....

I don't know enough about flow to really know how it affects drag. I'd expect the lower amount surface area the air stops on to have a big effect, but you could be correct.

[wpoll]

Originally Posted by MINIz guy

I don't know enough about flow to really know how it affects drag. I'd expect the lower amount surface area the air stops on to have a big effect, but you could be correct.

I don't really know squat about it either but it's pretty clear that the low frontal area of the OEM longitudinal rails will have little drag. The drag of the spaces underneath the rails is probably greater (pressure differences create drag - layman's description!). But even that is pretty low.

Removing the rear spoiler probably makes more difference at speed but it would make the car look neutered...

Adding lateral rails can typically add 5-15% to most car's drag coefficients.

Roof Racks a Drag on Fuel Economy | Berkeley Lab