A premium car like the Mercedes-Benz A-Class will always be more desirable when it is sold with a full dealer service history than one without. That said, if you plan to keep the car for the long term then you may prefer to save money and have it serviced outside of the dealer network. There are some excellent independent Mercedes-Benz specialists out there. And the quality of the work will be just as good as the dealer and a lot cheaper. The only drawback will be the fact your car may miss out on updates that are usually applied by the dealer during the annual service.