Kind of interesting on the mpg numbers, the 2007 N54 was rated 19/29, and 29 > 28. Don't know if anybody ever saw the story behind the EPA, but what is it, they test less than 5% of all cars and let the mfgs provide the numbers to them? Kind of like UTQG tire numbers, pretty much use at your own risk and of no use to compare one brand to another.
Say my car was rated 29 highway in 2007. Just because BMW reports a different (lower) number to the EPA doesn't mean that somehow as soon as their report was completed and someone in Munich clicked submit on a web page, my mpgs went down. They didn't change at all, it's the same car.