If the merc bore is bigger, then spigot rings will be needed. If it's smaller then you will need to rethink or change the Audi hubs......
just found this...although not 1992, starts from 1993
190 W201 95 to 93 5x112 35 to 42 66.6
66.6mm bore. Spigot rings will be your friend to make these fit.
Dan