Competition is good. Competition for buyers is what makes shopping for a compact sedan a worthwhile investment of time. All the players want your business. Which means all of them have to go the extra mile if they want to send you home in one of their products. The Nissan Sentra provides a good example of how this works. Ranging from about $12,000 to just north of $16,500, the retail price of a Sentra drops it into a slugfest with more than a dozen other subcompacts, an arena that includes pint-size hot rods like the Chrysler Neons and the ingenious variety of the Honda Civic. Achieving visibility in this realm is, to understate things, a challenge. But the Sentra does so, by the simple expedient of doing nearly everything quite well. The Sentra is an affordable sedan with a roomy interior. It's fun to drive with better-than-average handling, decent acceleration and good braking performance. It also rides well, operates quietly and provides an attractive, well-appointed interior. And like other Nissans, it's not likely to break.