Hi I have had mine since October 2019 and had the same issues with the smell of petrol, took it back to the dealership and they said it was some kind of valve that was not working, however after two weeks same again but due to work only had chance to take it back this week, they are telling me they will fit a new fuel pipe but will have to wait maybe a couple of weeks for it to come from Germany, so i will update when i get the car backI've had a c350e from new (2016) and only expereinced this after my recent major service. I took the car back to the dealer and they changed a high pressure pipe. The smell went away that evening (driving home) but it was back in the morning. I've been back to them and they can't smell it, but have arranged to keep the car for a few days in the new year. Apparently they can't do anything over the Chrismas period. My workaround is to drive with the climate control in recirculate mode.