I don't think windows up or down will make much of a difference for how long it takes for the car to sink... And you need to bang out or open at least one window anyway to get out. Let the windows up or down be dictated by personal comfort level and season... not dictated by a rather unlikely car submersion scenario.
Drowning cars does not happen too often.. Someone quoted statistics earlier in this thread - how many people are killed in regular (non-drowning) accidents? Divide those numbers and the ratio will help you put things in a perspective ... It makes sense to think through what you're going to do in such event and have a window smashing / seat belt cutter device at the ready, but unless your daily life puts you in location where car submersion is a likely accident scenario I wouldn't worry to much about windows up or down. That would be dictated by my personal comfort...
I would recommend to prepare mentaly and physically for what you're going to do in some scenarious (fire, car crash, car submersion and so on), but don't get to paranoid about it. My main focus in traffic is on driving safely and improving situation awareness (i.e. training my "accident avoidance radar").
Edited by MostlyHarmless (11/07/09 11:06 AM)