Mayor Sergio Chiamparino re-turned home from Salt Lake City, proudly carrying the official Olympic flag that will be safely tucked inside Turin city hall for the next four years while the city prepares to host the 2006 Winter Games. But Turin is running low on Olympic spirit. Now more than ever, the No. 1 concern here is cars. Despite talk of economic diversification and hopes for an Olympic boost, this is still very much a company town, Fiat's town; and the automaker is living through one of the bleakest periods in its 102-year history.