I can share my insights on the SMC entry level interview process with you.
One week after I applied via their online tool, I got a call to arrange a date for the first round of interview which was about 2 weeks after at their office in Munich. The interview itself was more or less a typical consulting interview. First, personal fit questions (why consulting, why Siemens etc., approx 10-15mins). Second came the case interview (approx 45-50mins). They didn't give me a case, though, they asked what I know about current issues and news about Siemens. I mentioned a few that I knew and in the end I had to analyse why Siemens acquired a specific company that I mentioned. In the evening I got a call from the interviewer, he gave me feedback and invited me to the second round.
The second round consisted of 3 case studies and a personal fit interview. The case studies were given this time but also related to real Siemens szenarios. So overall, its crucial you know as much as possible about Siemens and otherwise the normal case prep should be sufficient.
Hope this helps!