This 2006 530i is my fourth BMW, and the best yet. The combination of performance, comfort and excellent fuel mileage is unmatched in other vehicles. Like many others, I had concerns about the iDrive, but it has proven relatively easy to use and get used to managing. Interior comfort and quiet is exceptional, and those who complain about the cup holders in the 2006 must not have owned a BMW from the early 2000's, or they would appreciate the engineer's efforts to improve them. I have only owned the vehicle a short time, but it is delivering 23+ mpg in primarily city commuting. Highway touring is smooth, quiet and comfortable. Overall, this is the nicest all around vehicle I've owned.
The bluetooth system and dash display is terrific. The heated steering wheel and Comfort Access systems are extreme luxuries that are easy to get addicted to.
While the wheelbase on the 2006 is longer, it does not appear that any of the extra space went into rear seat leg room, which is lacking in a car of this size and price.