In The Martian we see airlocks that an SUV would fit into. Wastes air every time it's opened, even if pumped down. I suggest we make an airlock that clamshells down on a space suit and leaves the minimum amount of room between suit and lock for air to be reclaimed from. You could have banks of these is you needed to get a lot of people out quickly. And you could have all kinds of drama around this system, priorities, etc., of use, especially if you just had one.