Had that happen in an E30 - the throttle froze. Sudden temperature change from heated garage to minus 10. Scary, I had a manual transmission so i put my foot on the clutch - I thought that I was going to blow the engine - dealer blamed my floor mats. 2 months later BMW issued a bulletin - included a heaer for the throttle cable.

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07 X5 E70 4.8i
04 Z4 E85 3.0