After five months, I just discovered a key lock that sits immediately behind the left rear passenger headrest. Turning the physical key in it unlocks the trunk. I assume the intent of the lock is if the smart entry remote fails, or the battery is dead. Unfortunately, it is completely out of view unless the seat back is tilted down, and you can't release the seat back unless the trunk is already open. As long as you are aware it's there, and you have an emergency, it is possible, but quite awkward to reach around the headrest and use the lock. I haven't found any mention of it in the Owners Manual, but I'm sure it's there, somewhere. I'm probably the only Clarity owner who didn't know the lock exists, but I thought it might be worthwhile to let anyone who doesn't, know about it.