Just when we thought Buick was committed to unswerving conservatism, along comes a car like the 1997 1/2 Buick Regal. (Why is it a 1997 1/2? Go figure. Buick knows, but we don't.) Yes, the Regal embodies the virtues--roominess, smooth ride quality, lots of features--that go with Buick's marketing slogan: Premium American Motorcars. But it also goes beyond, treading perilously close to Pontiac's Excitement territory. This is particularly true of the supercharged Regal GS, which can match Pontiac's nifty Grand Prix GTP stride for stride, sprinting to 60 mph in about six and half seconds. That's pretty brisk for a conservative-looking mid-size family sedan. But we're not complaining. And we don't think you will either.