[AeroDan]

Regular 87 octane in our S60, 5-cylinder for the past year and a half. We've run regular 87 octane in our two Saab 9-5s (2.3L, turbo, 4-cylinder) since new in 2003 and 2004. In the summer we will run mid-grade, 89 octane, to alleviate some knocking in extremely hot weather.

 

[AeroDan]

I came across this.. The page is the same for the 4Cyl Models and the 2.5L models.. Interesting but not surprising.

We have been filling up with gas at our Costco in Texas. The fuel is rated "Top Tier". We have been very happy with the price, performance and pumps. They only offer 87 (regular) and Premium (93?) octane otherwise I may consider running mid-grade in the summer like we do on our Saabs. But so far, 87 octane has been running great in our 5-cylinder S60. Our mileage is averaging around town, 2-4 MPG higher in the Volvo vice our 2.3L, 4-cylinder Saabs on regular gas.