Armor all will do that.... a damp cloth to keep it clean will do nothing at all but keep it clean.

As for cracking... if you're going to keep the car for a decade, then use a window screen (reflective folding one) when you park outside.. otherwise, it's not going to crack (and I live in Phoenix AZ).

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BMW - X5 4.8i w/all US options packages, 19" Y wheels, White/Tobacco, Huper Optik 50% tint
Mercedes Benz - E320 CDI Park Assist, NAV, Folding Mirrors, Premium Sound, Voice Command, Sunroof, Auto Rear Shade, Bi-Xenon