Prevents car smoke and noise from different levz

A bit hacky, but I couldn't find a good way of acquiring car's z-level.

While noise from cars whirring above/below player could be desirable, it was rather confusing without any message suggesting that it's coming from above or below. And that would require precise car z-level info.

Smoke was easier, because it was an obvious bug. To reproduce it, you need to stand relatively close to car's location - for some reason being ~10 tiles and 1 z-level from a car will stop it from smoking, but standing ~3 tiles and 1 z-level from it will cause it to spew smoke.
Please use project bracket style.  Also I think we'd be better served by this moving into map::inbounds() so that we can change it in one place once we move forward with some z-level development.