It's true that the E46 M3 wheel offset don't fit E46 regular 3ers. But again look at how little the rear wheel gap is on the E46 3er and how close their stock wheels are to the fender edges already. Not to mention their rear fender liners are not rolled like the Z4. I guess some people just automatically assume you can't fit E46 M3 wheels on the regular Z4 either.