THOUGH the Allroad follows the Mercedes-Benz M-class and BMW's X5 into luxury four-wheel drive territory, the Audi offers both a high degree of competency both on and off-road in a station wagon - read passenger car - environment. That will immediately turn some people against it, but everyone else should revel in the Allroad's abilities. Strong, powerful engine performance, good accommodation and seating versatility, and an excellent collection of luxury and safety equipment are highlights of the package.