The Horch was an extremely rare automobile in its day and it's even more-so now. Only five were ever built. This particular car is one of just three that remain.
You may have never heard of a Horch, but it was one of four automakers that eventually combined to become the company we know today as Audi.
With Ford's new Mustang set to be unveiled on December 5th and the car's 50th anniversary in 2014, we asked collector car experts to tell us what the most important Mustangs through the years have been.