UP FOR DISCUSSION: - GM CEO Mary Barra Returns to the Hill. - J.D. Power, AutoPacific and Edmunds are out with their latest ratings. Who's tops? SPECIAL GUEST: Oliver Schmidt, General Manager, Engineering and Environmental Office, Powertrain and Fuel Strategy, VWoA All that and more with John McElroy, Autoline.tv; Gary Vasilash, Automotive Design and Production; Mark Phelan, Detroit Free Press.