Althrough I've had this car for only a short time, less than three weeks, I did drive a 2008 Impala for a year (company car). Because of the pleasant experience with the '08 I decided to buy an '09 when I had to return the company car. However I find the 2009 to be extremely uncomfortable as compared with the 2008, specifically the lumbar. It doesn't deflate all the way as it should, and it really really hurts my back (and others who have driven my car). This seems to be the way it is on all 2009's. (No problem with the 2008's.) I've been told "this is the way it is" and nothing can be done. This flaw should be corrected but I suspect it will not be because it's not a safety issue.
Allowing the lumbar to deflate completely for a much more confortable seating.