U.S. automakers closed out 2013 with weak sales figures, reporting a seasonally-adjusted sales rate of 15.6 million units in December when analysts called for 16.0 million.

Chrysler and Ford were in the green, but both missed analyst expectations. GM tanked 6.3% when analysts were looking for a 1.5% gain.

"An expected post-Christmas surge in [light vehicle] sales fell somewhat short of industry expectations," according to Wards Auto.

"Renewed upside was expected in the second half of the month, but overall December sales may show a 5% pullback after jumping 8% in November," Morgan Stanley's Ted Wieseman wrote clients.

Still, some cars were hotter than others. We picked out the 21 best-selling cars in December.