I would be very surprised if an e46 can tow more than 1000 lbs, there is no frame as such. Actually just contacted my local BMW dealer, they quoted 1000 lbs max, just an fyi.
Just another example of a dealer making up information instead of researching for the right answer.
I have the information for coupes, so I'll assuming its the same for sedans:
A 330ci is rated to tow 730kg (1600 lbs) without trailer brakes, and 1700kg (3740 lbs) with trailer brakes. In most places, trailer brakes are required when the trailer is past 1500 lbs, regardless of the tow vehicle.
The tonque weight has a maximum of 75kg (165 lbs), so be careful with the typically nose-heavy american trailers.
Source: 2004 BMW E46 coupe brochure (in German - its not listed in the American brochure) that I downloaded back in 2004. The bottom three rows are "trailer weight w/o brakes", "trailer weight w/brakes", and "tongue weight". Also, I found a
Dutch site that google translated for me.
Of course, don't go beyond what the hitch manufacturer says. The european hitch is a bit better integrated into the car.