>This seems... iffy. For one thing, ... At first I wrote "no oversized ventilation," but I shortened it during revision after thinking, "no, no-one would think

>This seems... iffy. For one thing, ... At first I wrote "no oversized ventilation," but I shortened it during revision after thinking, "no, no-one would think I meant something so dumb." Thanks for the correction. :P Yes, there will be ventilation, emergency lighting, and access paths. Those contingency systems are still much cheaper and take up less volume than the corresponding full-time systems. >it's a much worse idea to have your car constantly drive through the parking lot than to park it in the parking lot You say that as though it's obvious, but why? Parking lots are $$$, and this ~quadruples the density. It's not like you're paying drivers, so the only cost is a tiny amount of electricity (a parking robot would certainly use more, since A) it's heavier and B) it moves faster). I also presume the vehicles will be stationary most of the time, allowing them to de-energize power electronics in the common case. Wear-and-tear at those speeds is negligible, and multiple "lanes" means that if a car breaks down the other cars simply drive around it. Heck, at those speeds the following vehicle could push a disabled car out of a bottleneck (mature shared-use vehicle designs will likely feature non-scratch bumpers).