Battery in my 2018 E400C crapped out entirely the other day, after several months of running low and triggering messages to "check the manual." (I wasn't driving the car much at all due to the pandemic, working entirely from home, etc.; driving the car a few miles always brought it back to life for a while — until one day there was no juice at all when I got in the car.) Fortunately the battery's early death coincided with the need for my annual maintenance appointment, so I called the local dealer (Mercedes Benz of South Bay in nearby Torrance, CA), which put me in touch with MB, which in turn sent a flatbed truck to haul my car to the dealer (at no charge, I might add). Dealer deemed the battery kaput and replaced it — under warranty, free, no charge to me at all. I thanked the service advisor and out of idle curiosity asked what it would have cost if the car had not been within the warranty period. I was shocked when he said it would have been "about $650.00." When I commented, "Oh, I guess it's not a Delco," he replied, "Yup, that's Mercedes for you!"