I wouldn't call the E46 series a classic BMW - and I'm not sure, if it will become a classic sometime. It's more the 2002ti series that really become a classic of BMWs production. And the Z3 Coupé has more potential to be a true classic, then the Z4 Coupé!! But that's all my own opinion about that. And I think, it's difficult to say, if the new E-Class and CLK etc will become classics one time. Maybe the styling is to modern - same with BMWs and Audis current design. Those design elements are absolutely modern today, but no one knows, how this will be in future.