When you're talking about fuel economy don't forget about the oil usage. I have 3000 miles on my new 2009 S63 and I've put 2 qts. of oil in it already. Went to the Mercedes service counter and was advised--"That's pretty good, Mercedes specs are 800 miles a quart." I thought he was kidding, but Mercedes customer service confirmed. But, a little piece of mind---"it doesn't BURN oil --it just USES a quart every 800 miles. Why don't they put this in their commercials !