Thanks for your question, indeed a very interesting one. My most interesting consulting project (I hope this is what you're referring to as "case") was a 4-months long strategy projet in the E-Mobility (Electro-Mobility) business here at E.ON.
At hat time, a consulting team of 4 consultants supported the strategy development of the newly set up E-Mobility department in our company. We defined overarching customer and product parameters, the mid- to long-term growth of the business segment and the internal team set-up.
It was a great way to support new business development and learn a lot of new things regarding the topic "mobility of the future" in a hands-on approach. By now, E.ON E-Mobility has grown and evolved to one of the key E-Mobility players in Germany as well as Scandinavia and is enlarging its business to numerous other countries within Europe.
On a presonal note: during the consulting project, I decided to exchange my old gasoline car for a electric vehicle... :)