To make sure that we are all on the same page, let me say that certainly, most Germans speak decent or even good English and to a lesser degree other foreign languages. However, this doesn’t necessarily has an effect on their willingness to do business in another language.
I think the following quote by former German chancellor Willy Brandt still holds true to a great extend: “If I’m selling to you, I speak your language. If I’m buying, dann müssen Sie Deutsch sprechen.”
When you take part in some of the big German trade fairs that attract a large international audience, of which the CeBIT, Berlin’s IFA consumer electronics show and the Hannover Messe (Hannover Industry Trade Fair) are probably the most prominent examples. Many of Germany’s premier products are launched at one of the trade fairs.
This is even more true when you want to do business with German companies in Germany. I didn’t realize it was such an important part in negotiations before moving to France. I had thought that conversation or negotiations could easily take part in a language other than German, but I had to learn that this is not really the case. A bit astounded I learnt from French companies that having a German (born) or at least German-speaking team member opens them doors that would otherwise remain closed.
Now I can confirm, this is not a cliché, it’s the truth!
So don’t rely much on your German counterparts switch to English, some are likely to do that at a later stage but in the beginning it’s almost inevitable to talk in German.
To sum this up: You will leave a better impression and business becomes more likely. I would also emphasize on the cultural aspect. How do Germans do business: educate yourself on points such as being on time, handshake or not, Du or Sie and business hours among other.