aldo, a car is a car, a trailer hitch is a trailer hitch...

however, you bought not just any car but a BMW... the bavarian engineers are well known overengineering some of its macinery (and underengineering some others)...

take a look at this link to see parts included and take a look at what your Uhaul guy is selling... Home Page > Search > Bmw Hitch > ES#185392 Trailer Hitch Kit - 71600009711

imagine, you have the strongest truck, strongest hitch and you are pulling a 6000 lbs trailer... and you are using a wooden stick for a pin... how far will you tow the load? not far... the non-factory kits do not mount to designed spots, they screw to sheet metal or drill a hole in rear carrier and hook up to it...

this is your car, this is your call... check out options, make your own decision