Originally Posted by deanyel

Thanks for those facts, but those are some pretty loose facts. The two MBs require 91 octane, not 93, and the Volvo claim seems suspect as well. Here's my personal experience - which I would characterize as anecdotal rather than factual - in a car that requires premium fuel the additional cost of premium fuel is justifiable in better mileage. I have always found this to be true. Try running a 6.3 on regular. You may be proud of your 24-26 highway numbers but those are not good numbers for a 104 motor on the highway. I get 29+ in an S320 on premium which easily justifies the approximately 5 percent premium price premium.