First off, the culture wars don't rage nearly as venomously in Germany as they do in the US, but that doesn't mean there's no political/ideological polarization. A hefty portion of the vote is determined by religion and class. If you're catholic you're way more likely to vote CDU, unless you're lower or lower-middle class and preferably a member of a labor union. If you're protestant or have no official religious affiliation (as many people in the east do) and/or are unionized, you're far more likely to vote SPD. This is why the SPD gained a huge structural advantage from the reunification (what with catholics becoming a minority nationwide), even as it has been steadily loosing union support, as the power of organized labor has been on the decline just as it has in the US.

Secondly, it's true though that Germany isn't nearly as polarized as the US. There are currently way more swing voters in Germany than in the US (especially when you take the 2004 elections as a standard). I would guestimate the percentage of swing voters in the current elections anywhere between 20% and 40%.

Final point, ideological diversity is hampered by the parliamentary system - especially the fact that parties mostly vote as blocs. So the views and votes of the individual representative matter far less than they do in the US. Which makes the system less democratic, in the sense that there's less room for individual views; but at the same time, it also makes German politics less personality-driven.

If you can't convince them, confuse them. (Harry S. Truman)