Lawmakers are investigating after Volkswagen admitted it installed on-board computer software designed to cheat on government emissions tests in nearly 500,000 of its four-cylinder "clean diesel" cars, starting with the 2009 model year. According to an advance copy of Horn's prepared remarks, VW plans to withdraw applications seeking U.S. emissions certifications for its 2016 model Jettas, Golfs, Passats and Beetles with diesel engines.