Navistar, Warrenville, Ill., announced on July 28 that it will be raising prices on its International trucks by $6,000 to $8,000 in order to comply with new Environmental Protection Agency emission requirements for diesel engines. Prices for vehicles with midrange diesel engines will increase by $6,000, while prices for heavy-duty diesel engines will jump $8,000. Increases will come as a non-discountable surcharge applied to the vehicle’s base price.