If you like new cars, you probably love their smell: the mingling scents of taut leather, shiny propylene, and new rubber. Used-car dealers have even been known to spritz the interiors of "pre-owned" autos with an ersatz version of this bouquet. But the real new-car aroma can be hazardous to your health. It has been known to cause headaches, irritated eyes, and even drowsiness, which can be especially dangerous when you're driving your new car home from the lot. According to Daniel Nesa of the Renault Technological Center in Paris, "almost every car manufacturer in the world is concerned about new-car smell."