Hi gang - my recent experience here FWIW. I am ordering a new x5 (2010, maybe 2011?) and have talked to 2 different BMW dealers here in Rhode Island USA area. Both gave me the same info WRT roof rails:

- Roof rail option for $100 MSRP (if ordered before production with factory install).

- Post-factory dealer roof rail install - much more expensive due to the additional removal of headliner, etc that is required. I didn't get a quote but am ordering mine with roof rails from factory.

Luckily, I like to do lots of research before buying a car, so I thoroughly looked in the brochure and the "build your own" feature on BMW. There are so many options / packages that I am careful to be sure I'm getting exactly the options I want.

Since the X5 has less room than some alternative vehicles (Acura MDX, Audi Q7) I am very happy to have the roof rails - we'll almost certainly need them for a roof cargo device on long road trips (wife, 1 new baby, 3 dogs). A few years ago we had a used Ford Expedition ('99) that was full of volume... but it was ready to be retired after about 80K miles and we have been SUV-less for 3 yrs now.

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My current cars:
'94 Mazda RX-7 / Green / Tour pkg / 110K miles
'08 BMW 550i (9/4/2007 ED & 11/7/2007 PCD)/ CB / All options except AS & LDW / 38K miles
2010 X5 xDrive30i /Alpine white over sand beige/Sport Activity/Premium/Cold Wx/Rear Climate/Technology/Active Ventilated + multicontour seats/ 3 miles