On the first start of the day having been left overnight my W204 has taken to starting on a fast idle (~ 1,500rpm) which it holds for approx 12-15 secs before settling back to the usual ~ 850rpm. This seems to have coincided with the very cold snap we're having, but I don't remember it doing this in the cold weather early last year. Having said that, I think that lately the overnight lows have been three or four degrees lower than I've experienced witth this car before. Is this a feature or a problem? Anyone know, or do I mention it to the dealer when it goes in for its A service in a couple of weeks?