I've installed an American (Curt) aftermarket trailer wiring system into a modern German car (Mercedes). The system worked fine after I replaced some of the crappy splices that gave intermittent connectivity. It did not enable key features such as active sway control, disabling parking sensors etc. But it was cheap ($60). I installed a high quality German-made aftermarket trailer wiring in to my previous BMW (Westfalia brand, $150), and it worked flawlessly/seamlessly and equivalently to an OEM module it even fit into the module slot under the spare where the OEM module fits. Wiring was a slight PITA because I had to tap into wires hidden in a huge bundle behind the rear seat outer bolsters. And most recently I installed the BMW wiring/module into my E70. The OEM wiring/module was by far the easiest to install, but cost $90 more (cost to reconfigure vehicle software). Based on that experience, I recommend the OEM module/wiring over the Westfalia module, and I do not recommend the typical American wiring module (unless you tow teeny loads on rare occasions). BTW, my OEM BMW module in the E70 works fine with my trailer LED lights. I've heard of problems and pre-purchased an adapter, which I ended up not needing. This could be due to the fact that my trailer has 16 clearance lights (8 upper and 8 lower) and 4 tail lights (each of which has something like 10 LEDs). So, there's a total of 56 LED's that make up the load on the BMW trailer module. I guess that's enough to provide a sufficiently high resistance to be compatible with BMW's tail lamp diagnostics.

They had to cut a square out of my bumper cover to get it to fit.

OEM hitch requires cutting the bumper cover as well.

Did further googling and the trailer coding can be done by NCS Expert. So more motivation to get that set up.

Same as all audio and alarm install guys-here and in Europe. I have seen unthinkable things done :wow:

Bumper cutout:
You don't have to cut out as much as BMW recommends in the official install instructions. I made the smallest cutout possible for my bumper (LCI), which involved a center section of the lowest silver trim and only a very small cutout in the middle black section. The cutout is small enough that all you see is the receiver end. Everything else remains hidden. I think it's a lot nicer, visually, relative to the OEM install process which creates a big square hole in the bumper. I did use a stack of 4 AN washers to tilt the 7-prong plug downward, which is important if you don't want to cut out the bumper any bigger than the 2" receiver.

Personally, I would not use a Uhaul hitch, but I would reinforce the connection of the receiver tube to the cross bar on the OEM hitch with an extra plate.

Uhaul hitch installed
 

Yes, I had mine installed at Uhaul. The guys that installed it had done 20 X5s prior to mine. He knew all the things that needed to be done. Time will tell when I hook up the lights to the trailer. All I will be towing will be Jetskis at this time. Don't foresee anything heavier in the future. It is warrenteed for 2 years and he said any problems come and see him.

Got a scare after he parked it with the emf on. I could not get it out of EMF and thought it might have been the wiring that screwed it up. Apparently the EMF had a time out. You have to wait awhile and then it works. If you keep trying it immediately it won't did engage. Found out the hard way.

End of story
Regards
WJ;);););)