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.