Originally Posted by Cobra1169
Has anyone purchased an additional Key to have as an Emergency Key for their Interstate and maybe kept in a Hitch Vault? If so, how much should I expect to pay. I'm assuming that both a Key and Fob are required to access and start the vehicle. This would be for a 2014 model.
Late-model keys have an RFID chip built in that the ignition switch must detect in order for the key to turn. Side note, dead chassis battery means no detection, too, so even the right key won't turn if the battery is dead. Another side note, if you have another vehicle with an RFID key, do NOT keep both keys on the same ring; the Mercedes ignition is sensitive to pick up the other key as well, and lock your ignition switch until the other car's key is removed from the key ring.
Door-only key has no RFID chip, so even if it's inserted in the ignition it won't start the vehicle.
I have a hitch vault, but seldom use it because there's usually something else attached to the receiver, either a cargo tray or my toad's towbar.
I'd recommend getting a spare ignition key AND a door key. Store the door key somewhere outside the vehicle, hidden but accessible (on the roof might be good; no one can see up there without a ladder and so few people look up; they look behind the bumpers and such). Then store the spare ignition key somewhere inside. Maybe clipped to one of your low-point drain valves, so a potential thief would have to remove a drawer or a cup holder or something to find it.
Side note, the very best anti-theft lock is a (combination) padlock on your driver's seat swivel. Swivel the seat so that it faces backwards, and slide it back (toward the front of the vehicle since it's backwards now) so that it's in contact with the steering wheel. Then padlock the seat swivel/slide mechanism so the seat doesn't move. I guarantee no one can drive the vehicle with the seat like that, even if they find your spare ignition key.