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      06-17-2007, 09:28 AM   #52
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Drives: 2007 E90 335xi
Join Date: Jan 2007
Location: Jemez Mountains

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Originally Posted by ENINTY View Post
Considering the interior is vented, heat inside the cabin would not pressurize the cabin to the point where it would break the glass.
For a sunroof to blow out due to cabin pressure....., that must of have been one hell of a fart.

It's not so much the increased cabin pressure from heat, a/c, concussion farts, etc., but more that the air increases speed as it moves over the car. Higher speed air has lower (static) pressure. So it's the decrease in pressure over the sunroof. Very roughly, airplane wings use this same effect to create lift.

In any car, it's the same reason when you close all your windows when driving at highway speeds, your eardrums feel the pressure increase. At least mine do

Is the pressure difference enough to shatter a crappy sunroof? Maybe. But whatever does shatter the sunroof, it's not a surprise to me that it blows out.
2007 E90 335xi || Sparkling Graphite || Terra || Burl || 6MT || Premium || Sport || Cold Weather || Sirius || Comfort Access
ED May 2007 Report
My 335xi in the Alps