I just went through the research on this and concluded it wasnt worth the trouble. Do a search of the archives using importing/gray market terma and you will come up with lots of info and links.
If you re-export your car, and have it here for less than a year no mods are needed.
You could also look into selling it in Mexico.
There are, by the way, lots of nice inexpensive used Benz to be found here!!
92 500e, 85k, silver/gray,all stock.
96 Club Wagon,Hypertech chipped( College Hauler)
97 320 SL 50k
1980 BMW e21 323 Baur conv.
1990 300GE 99k