Mercedes GT Roadster starting problem solved

I have a GT Roadster as well, and your issue sounds eerily familiar to what I went through a few months back. My car was also struggling to start, especially on colder mornings. I also suspected the battery at first, but the problem persisted even after a jump start. It could be the battery, but I suggest looking at other components as well.

Thank you for your response. Could you elaborate on what you discovered during your troubleshooting process? Did you also experience any issues with Terminal 30, or notice any unusual voltage drops? Any details you can provide would be greatly appreciated. I'm trying to avoid a costly and time-consuming diagnostic procedure at the workshop, if possible.

I never got into the electrical diagrams, but my mechanic eventually traced it back to a faulty relay that was intermittently cutting power to the starter. It wasn't a complete failure, but enough of an interruption to cause starting problems. It might be worth getting it checked out professionally. Saved me a lot of guesswork and potential damage.

I appreciate your input. I took it to my local shop, and as you suspected, it was indeed a faulty relay causing the intermittent power interruption to the starter motor. Replacing the relay and performing a thorough system check has resolved the issue. The total cost came to 290€. Thank you again for pointing me in the right direction!