In the German system, you make two votes: one for your local MP, and one for a party. Half of the Bundestag is made up of directly elected members, the other half assigned by proportional vote. So, normally you pick the rational choice of SDP or CDU in your riding, but if the Greens or the FDP or Die Linke or Piraten or whoever actually fits your views better, you can still vote for them in the party vote and have those views represented. Except if you're the FDP and you're so terrible that you fall under the 5% of the vote required for proportional representation. lol FDP.
In the American FPTP experience, the vast majority of Congressional districts are a false choice anyway, so politically skewed towards one side or the other that they're uncompetitive and will always be represented by one party or the other, depending on the demographics. In the competitive districts, the economics of the situation (which are different that the British system with even less incentives for 3rd parties, but are still mostly applicable) dictate a two party system. You're better off supporting a center left or center right candidate that represents some of your views instead of voting for something who actually represents your views, because ideologically "splitting the vote" only helps the other side. And those individual representatives are rarely held accountable for their actions, simply because the average voter doesn't care enough unless there's a scandal.