Neighborly Ind. car dealers face troubles together       AVON, Ind. (AP) - Danville Chrysler Dodge Jeep and Dugan Chevrolet Pontiac across the street have waged a friendly competition in Avon for more than 40 years.    But the two suburban Indianapolis car dealerships seen tough economic times lately. Sales have slid, inventories are down, and now both dealerships face dire warnings that ...