I have a 2001 V70 T5 and I always run regular (87). So much depaends on driving style and conditions. I live in Vacaville California and it is flat here. If I was drivining the mountains or pulling a load, I'd run premium. I don't see that much difference in performance, as I am a very easy driver, so I don't need the extra omff that premium provises!!! I also only run Chevron, and that too may have something to do with it. While it seems rather strange to me, and I can't explain it, I actually get better gas mileage with regular than premium, but will acknowledge it probably fits my driving style. I'm sure most other forum members will not have these results, just too many varibles.

Jerry