A carryover feature found on all Mercedes that allow only front and rear running lights to be illuminated when parking on the side of the road. Especially helpful if your vehicle might be partially obstructing traffic. You can illuminate the left or right side, depending on which side is vulnerable. With just the front and rear left or right running lights illuminated allows leaving them on overnight without significant battery drain. Americans tend to use the safety flashers for the same purpose with risk of running down the battery over extended periods.