The owners' manual says 87 octane required, 91 premium recommended for optimum performance.

My BMW owner's manual says 91 octane premium required for our X3.

In both cases, I follow the owner's manual. Can't go wrong, no? (lol there has been many a thread on this on the BMW forums)

 

i always use 89 octane for all my cars, my 01 camry, 00 es300, and my 92 accord, havnt had any complaints, all the cars are running strong

 

Put 87 gas in, and stop wasting your money.

 

I would say test both Octane levels and compare mpg after a full tank of use of both.

Although I have a different engine (1UZ), when I tested both the $$ savings from the 87 octane was offset by the decreased gas mileage. Actual cost per mile was least expensive using 92 octane.

The adjustments the ECU made with the 87, which included a slight decrease in power, and retarded timing, made for quite poor gas mileage.

Results were roughly 17mpg with 87 and 19-20 with 92.