Great topic...I buy my cars new and keep them till they completely fail (like transmission failure after 253k miles) and they still look gorgeous! On that note, I've washed my cars many times in sub-freezing temperatures probably as low as 20F in my driveway, but the last time I did this, I turned my driveway into an ice-skating rink, slipped hard, hurt my elbow, and slid all the way down the driveway on my butt into the gutter. Since then, I won't do it unless it is at least 35F and even then, only in the sun. I just try to tell myself I've applied such a good coat of wax on before winter season, everything will be OK! I'd rather wait till it's a bit warmer than use a brush equipped auto car wash, or even a brushless facility which I hear rely on harsh cleaners in lieu of the brushes.