Group: Members
Posts: 64
Joined: 14-January 07
Member No.: 3,933
Drives: 2007 Toyota Avalon Limited
Location: Washington State, USA
Not sure about the '08, but the '07 owner's manual recommends running 87-octane. Using higher octane (according to the manual) will result in better performance.
I've put nothing but 87-octane into mine for the past 38000 miles. It runs great, gets great mileage and I wouldn't hesitate to put it up against my own Mustang GT in a 1/4-mile run.