Some are lightly disguised future production vehicles, while others exhibit an environmentally friendly theme.Here's a look at a few of the more interesting concept vehicles on display at the show, which closes Monday: AUDI ALLROAD QUATTROThe German automaker has been building all - wheel drive cars for years, so it's no surprise that a beefier version of the A6 station wagon is on the way.The Allroad Quattro show car uses many of the same mechanical and suspension parts as the A6 wagon but wears a sport - utility
wagon body complete with large fender flares and huge tires.