Reducing condensation inside cars in General Toyota Guides Posted May 21, 2017 A very simple way to reduce the amount of condensation that can build up inside the car is to leave your front windows slightly open as this allows the circulation of air. Of course, if you live in a built up urban or city area and park the car in the street then you may not be keen on that idea. Living in the middle of nowhere I don't always lock my car overnight when it's in my drive so leaving the windows open by an inch or a half inch is no big deal. Having stripped out my A/C completely I don't have it to aid the ridding of moist air particularly heading into work at 4.30.or 5 am so rely on the old fashioned heater and an open window. Speaking of windows I wholeheartedly agree with the point about keeping the windows as spotlessly clean as possible. Never mind the condensation there are so many very good reasons to take the extra time to do your windows that there's no real excuse not to. Vastly improved visibility being the critical and most obvious reason but when I say vastly I'm not exaggerating at all.Windows get dirtier over time so you tend not to notice how dirty they've become. Like all the most annoying and mundane chores in life if you do it regularly you find that it takes less effort each time. Do it weekly in 15 minutes or twice that and more if you leave it months at a time. As an ex-valeter I can also add that clean windows make a bigger difference to the overall look of your car than anything else. Obviously it won't make up for dent, scratches and rust spots but a nice car with clean windows looks 100 times better than a nice car with dirty windows. Sounds stupid, one of those things self confessed experts always seem to come out with but you'd be surprised at how much things that people don't consciously notice about a car contribute to the overall impression. If ever you're selling your car and are short on time, do the windows and the door shuts properly and just wash it, it'll pay dividends lol.