When Toyota launched the fourth generation of its popular sedan last year, the automaker's stated goal was take the Camry, already the benchmark for family sedans, and make it even better. A less-public goal was to make the Camry the best-selling car in America, bumping aside perennial winners Ford Taurus and Honda Accord. To do so, Toyota devised a simple strategy: Give the car more of everything without sacrificing the traits that made the Camry so successful. The new model was slightly larger, the interior more spacious, the ride and handling more refined, and it sported a longer list of convenience and safety features. Perhaps most important, the price was a few points below comparably equipped '96 models. It was a smart plan. One year later, Toyota has met the challenge it set for itself. When sales numbers were tallied at the end of the 1997 model year, Americans had bought 385,814 Camrys, 10 percent more than last year, edging out Accord and Taurus. With that kind of success, it's not surprising the 1998 Camry offers relatively few changes over the 1997 model. There are, however, several significant improvements, including the availability of side airbags and an engine-immobilizing anti-theft system. These days, even winners can't slack off.