I had a hard time deciding how many stars to give this.It's not at all perfect, but there aren't many alternatives.Curt should be rewarded for helping us 5 series folks out, but the price is rather high when the negatives are considered.
The black finish is wonderful although I don't think that's very important.What is important is the strength.To that, I can only take their word provided you stay within the tongue weight and trailer weight.Perhaps I'll update this summer.
I need to point out that this hitch mounts to the sheet metal around the spare tire well; not the frame.I think this relates to the Class I rating.
There are two negatives:
1) The thinner bar that has four holes is straight.But the BMW is slightly curved here.What to do?Well, either the car's sheet metal will bend or the hitch bar will (or maybe both?).I decided the hitch was more replaceable than the car, so I bent the bar myself, before bolting in place.Of course, this chipped the finish.In my opinion, this should have been addressed.
2) The unit comes with a receiver.But the black finish was applied so heavily that it built-up at the and that prevented fitment in the hole.Yes, it can be addressed, but for the price I expected it right.
My brief experience with the hitch pulling the boat out of the shed was positive.I got on the brake hard a few times to see what happened.Answer?Not much.
My last comment: I used construction glue between the hitch and the body to prevent water from rusting out the car.Like I said, the hitch mounts to the sheet-metal and you can't afford that to rot away.Yes, it may increase the strength although I would not even think to suggest you tow more than they recommend!
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Curt Manufacturing 11179 Class I ReceiverProduct Description: All CURT hitches feature WeatherTite construction, which prevents rusting from the inside out by sealing the main body of the hitch. The receiver tube has an open back end to allow for easy cleaning and for dirt and moisture to pass through and not get trapped as is common with other brands of hitches. All CURT hitches come with mounting hardware and installation instructions. CURT is the only hitch company in the industry that mechanically de-scales all of our hitches before applying a thick powder coat finish, which is baked on for a high-gloss, smooth surface. CURT trailer hitches are simply the most attractive, most durable and toughest hitch on the market. You won't find better quality and value anywhere!
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I have to say, you should feel comfortable doing work on the car, have good power tools, and not have a bumper that goes very low that you have to cut.You will probably need a helper. 
