Originally Posted by AzNMpower32

BMW used to be more specific on these requirements. In the 2007 3er manual, it states that 98 be used for the advertised economy and power, with lower grades to 91 possible (the N54 engine requires 95 minimum).

In the new X3 and 5er manuals, it simply states quality of the fuel is more important, and that 91 is the minimum octane level.

Wonder if and why they're leaving things out of the owner's manual.