Hello everyone. The manual says 89 octane is OK for the 07 MCS and that is what my dealer filled my tank with on delivery. My 2005 Cooper recommended 91 minimum and I ended up using 93 because I had trouble finding 91. Anyone have any opinions on the 07's and octane? I'd certainly like to use the less-expensive 89 but don't want to sacrifice performance or mpg's for the cost of gas.

Astro Black 07 MCS. Sport, Premium and Cold-weather. Chrome-line in and out. English oak/piano black. Hifi sound. All-season 17" run-flats.

 

The car has an anti-knock sensor, and will retard the timing to compensate for the lower octane gas. That translates to less power and efficiency.

Put premium in it.

 

What about 91 vs. 93? I haven't looked extensively, but noticed that a local Shell station only had 91. Is there a power loss using 91?

 

No power loss with 91. The ECU might adjust for the slightly higher octane (93), but that's not detrimental.

 

Great advice. Premium it is. Thanks.

 

The owner's manual for the 2007 MCS (at least mine) says 91 is recommended, but it can run on at least 87. I'd go with the recommended.

 

ditto

 

ditto