Horch 12

The Horch 12 was the first and only Horch model series to be powered by a V12 engine, positioning itself above the Horch 8 series. However, the idea of bringing a luxury car with a twelve-cylinder engine to the market came at the worst possible time, shortly after the Wall Street crash of 1929.

The first model in the series, the 670, was presented at the Paris Motor Show in September 1931. The 670 was a huge two-door, four-seat convertible, which used the same chassis as the Horch 8 with a wheelbase of 3.45 metres.

In 1932 the 600 was introduced at the Geneva Motor Show, which was structurally and mechanically identical to the 670 but was available as a four-door limousine or six-seat convertible. These two additional seats were made possible by using the chassis of the 500B with a wheelbase of 3.75 metres.

23 Horch 600s were produced until 1933. After the disappearance of the 600, only the 670 remained, of which 58 would eventually be built until 1934. A total of 81 Horch 12s were produced, of which four 670 convertibles survive.^[5] The Horch 12 did not receive a successor, so the Horch model range from then on consisted only of 8-cylinder models.

The Horch 12's V12 engine was designed by Werner Strobel and Horch's then-Technical Director Fritz Fiedler^[5] and consisted of two banks -of six cylinders each- in a 66-degree V configuration with a total displacement of 6021 cc, and featured a crankshaft with seven bearings. The camshaft, driven by a chain with an automatic tensioning device, was located centrally between the two cylinder banks and operated the horizontally arranged sidevalves via rocker arms. The sealing surface between the cylinder block and head, and thus also the head gasket, was angled. The engine produced a maximum output of 120 horsepower (89 kW) at 3,200rpm.^[7] This power was transmitted to the rear wheels via a manual four-speed transmission with ZF overdrive. The 670 model could attain a maximum speed of 145 kilometres per hour (90 mph),^[8] with the 600 model slightly slower.

The engine was equipped with hydraulic valve control, a system that was decades ahead of its time.^[6] The driver could supply lubricating oil to the cylinders and pistons via a dedicated line system from the dashboard, which increased compression and thus facilitated cold starts.

The chassis featured rigid axles with leaf springs, which was common practice at the time. The hydraulic braking system with its Bosch Dewandre brake servo, however, was ahead of the usual technical trends of the time. A special feature of the Horch 12 was its permanently installed hydraulic jacks for changing wheels.

• PL4 = 4 door Pullman limousine
• PC4 = 4 door Pullman convertible
• Cb2 = 2 door Convertible

Only a handful of Horch 12s are known to survive today (four confirmed convertibles according to most sources, though some references mention up to six). Surviving examples are displayed in museums including the Audi museum mobile in Ingolstadt, the Cité de l'Automobile in Mulhouse, France, and the ZeitHaus at the Autostadt in Wolfsburg. The model remains a symbol of Horch's engineering ambition during the final years of independent luxury-car production before the Auto Union era and the onset of World War II.^[9]