I think it's just market trends, and nothing really to do with performance, and this also goes back to when I think Diablo asked about why the Z didn't have hugh hp gains over the previous Z. Your average consumer doesn't really care about or need 300 hp in their car (and there are some people I know who I wouldn't want to have that much power in their car). I think your average person just test drives car and if they're satisfied with the amount of pickup the car has then it's a sale, they don't really care about quarter mile times and if they can beat whoever at the track. My dad's 88 accord had less than 100 hp and our 93 voyager has only 150 (less than my Civic) but they're still fine to drive around town....it really doesn't take that much power to move a car around. Turbochargers may be reliable, but it's another couple grand of development and equipment costs that go into a car, and that extra cost is passed on to the consumer.