Arguably. While it is true that the SPD has departed from its roots as a socialist working class party they can still be considered "leftwing". I don't want to go into too much detail here but Hannelore Kraft has run on a pretty leftwing platform of social policy (offering free childcare, as but one example).

When compared to american politics... pretty much every german party except maybe the FDP can be considered "leftwing" or even "socialist".

> Saying that the modern SPD is leftwing

In the NRW elections, between the Linke (which are a lot more popular in the eastern part of Germany), the Pirates and the Greens there's 21.6% that's arguably further left than the SPD which, given that and the fact that it's got about 39% of the vote here, might well be considered centre-left these days when looking at the relative spectrum.