Roofrails, good or bad?

[ASV]

I think it's just a compromise not as good as removable racks better than full size racks
Aerodynamicly however I think it would promote a vortex along the top of roof in even a lite cross wind

[freebeard]

That's exactly why NASCAR uses them, to kill lift when you get sideways.

https://en.wikipedia.org/wiki/Wing_fence

Airplanes use them to delay stall. Race cars use them to channelize air in the diverter.

[Jack-Lee]

i used such "reels" for reduce sidewindproblems on my velomobile. On a very aerodynamic car it could usefull

[Hersbird]

Somewhere around 2001 and 2002 some grand prix and Monte carlos came with roof fences in a special edition. A knock off smaller version of what was on the nascar cars.
I love gimmicky low production crap like that. Also see the 80's Monte Carlo aero coups with special back window and the greatest of all time, the Superbird and Daytonas.