Interesting story... I reached out to Curt regarding the issues I experienced with the hitch. This included the cutting of the underbody panel, the hitch not fitting the car correctly without grinding, and the fitment of the hitch with the bumper which made installation difficult.
Curt brought in another Model 3 and confirmed that the fitment was not correct on some models. They redesigned it with better tolerances and sent me the updated design, free of cost, in early April. I installed it last weekend. Here are a few things to know if you go with the Curt hitch:
- The updated design fits without grinding the hitch.
- You will have to cut away more of the bumper underpanel than they indicate. I know they say approximate, but that assumes you don't need the chain loops (you can cut them off before install if not needed and their measurements will likely work).
- The ears of the hitch push against a section of my bumper on both sides causing a slight bulge between the bumper and the underbody panel (see pictures below). I was hoping they would fix this, but perhaps it's something to do with my build?
I went with the Curt because it was more than half the price of the EcoHitch and I didn't care about hiding the hitch - I actually like the look of it. If you have to cut your underpanel, I don't see the point of purchasing the EcoHitch except for cosmetics. After installation of the Curt, I drove from Chicago to Houston and back. I didn't notice any increase in wind/road noise or a quantifiable affect on range.
I am annoyed that they didn't correct the issue I have with the underbody panel being bulged out. It makes the bumper installation more difficult - while someone holds the top in, I pulled the bumper/underbody panel down so it clears the hitch. If I didn't do this, the bottom rear of the bumper was pushed out and all the bolts wouldn't align. Once I cleared the hitch, everything popped into place. My recommendation is have someone start from the center top of the bumper next to the trunk, and someone under the car works to align the bolts of the underbody panel.
I believe that Curt designed the hitch correctly for their example vehicle, however this is Tesla's first foray into mass production. They likely had tolerance issues and changes mid-production compared to experienced automakers, causing fitment issues Curt doesn't experience on other vehicles from established automakers.
See my photos below. With the exception of the bulging (which is only visible if you lay down next to the car), I'm happy with the updated design.