I'm soliciting ideas and opinion about roof racks and cargo boxes for occasional highway use (like maybe once or twice a year) on my E39. Actually, I've already purchased a used Thule roof rack specifically designed for E39. It bolts into the roof like an OEM BMW rack after popping off the BMW protective covers on the roof, using a screwdriver. This rack looks plenty sturdy & should stay put.

Cargo Box:

Will a 15 cu ft or 18 cu ft solid plastic "Sears Cargo Box" be too much for this setup? What about the longer 67" 20 cu ft unit they sell for station wagons and SUV's...would it blow off at 80 MPH or overhang the front window? They are are all reasonably priced at $120-$170. Internet prices on name-brand cargo boxes are about 2x to 3x, so now I understand why most minivans I see at campgrounds have Sears boxes. The 15 and 18 cu ft models are about the same length as the roof (50-55"), so overhang in the rear will be minimal. The 20 cu ft model is 67" long (about 12" overhang). The cheaper gray colored 18 cu ft model they sell is sort of fat-looking and probably isn't too sleek in the wind. I do like it's squar-ish interior dimensions, though. Some of the lower profile $400 Yakima and Thule units look like they'd be good for transporting a hockey stick (lol).

Thanks for any opinion about E39 sedan roof racks and/or cargo boxes.

As an alternative to the sometimes pain in the neck roof boxes, not sure if you realized Thule Racks has recently aggressively moved into the soft sided roof bag market for transporting luggage and cargo gear. The roof bags mount to the base rack load bars (both thule load bars and also factory roof rack crossbars) and provide darn near the same cargo volume as a cargo box. The most convenient aspect is that you can remove the bag without any hassles and store it away no problem. The cargo box is alot of times hard to store away when you don't need it. The Thule 866 Escape II roof bag is probably the best luggage bag because it's waterproof and has a whopping 15 cu. ft. load capacity! Unless you need to carry skis or snowboards, the roof bags are a really good alternatve and way cheaper than a cargo box.