GM Sales Down 6.3 Percent in December, But Up 7.3 Percent in 2013 Jan 3, 2014 | News GM Sales Down 6.3 Percent in December, But Up 7.3 Percent in 2013 All four GM brands were down in December, with Chevrolet worst at an 8.1 percent decline, but …read more Share this:FacebookTwitterPinterest