You must enroll in the appropriate German language course for engineering students, and follow the recommended outline of courses available from your advisor. This program is made possible by spreading the courses over a five-year period rather than the usual four years. There is no tuition charge for the one-semester professional internship spent in Germany, for which you will be paid. Thus, your extra tuition will only be for one semester. Most students begin with no prior knowledge of German.
Any background does mean a head start, though.
Germany is the strongest economic force in Europe, with critical access to the emerging Eastern Europe. There are huge German investments in the United States, as well as American investments in Germany. The IEP has proven a clear demand for American trained engineers with good German skills. Yes, the IEP runs a sequence of specialized German language courses for engineering students, which help prepare for the internship abroad. If German doesn't agree with you, then you may simply revert to the regular engineering program.