Yesterday while driving home at a low traffic speed(about 25MPH) I heard a loud whoooooosh, like a tire going flat quick. The first sound was longer than the second time I heard it. I thought I blew a tire. When I got home, all gauges were fine. Temperature was good, no noises etc. No fluids, no flat tire(s). But now my average mileage indicator is way off from what it was before the noise. It was around 21+mpg, now showing and very erractic 16-17mpg. This is the average, not instantaneous. I also "think" that the faint whine of the turbo is gone. Hard to tell power b/c I have not driven on wide open roads. But there seems to be a faint power loss. Could I have lost the turbo? Is there some type of hose that would blow off to make the noise I heard? It was like an air hose with the blow gun nozzle on it releasing air. It almost sounded like it was going round and round, just like a tire losing its air going round and round, albeit briefly the two times I heard it. This is on a 2002 V70XC with 80K miles. Thanks.