The first official practice session for the 1933 Avusrennen took place on 18 May 1933. A heavy rain drenched the track, and
Daimler Benz drivers Merz and
Manfred von Brauchitsch wanted to try their heavy SSK streamliners under those conditions. Witnesses reported the cars were sliding in several locations on the track and it was very difficult to drive. A few minutes after 13:00, Merz crashed his SSK on the long straight, overturning near the
Grunewald station and nearly from the finish line. At the place of the accident, the surface changed from
cobblestones to
tarmac, and traces of the car trajectory were clearly visible on the cobblestones - but suddenly ended. The next mark left by the vehicle was found further on, where the car hit the ground again. The Mercedes-Benz crashed into a cement milestone on the right side of the track, and, according to the single eye-witness, it somersaulted and rolled several times. The car stopped with its wheels in the air near an embankment.
Cause of accident Investigators later concluded Merz had lost control for a few moments. A fundamental difference between Brauchitsch's and Merz's Mercedes was determined to have caused the accident. Brauchitsch's had a differently streamlined body than Merz's: on the Brauchitzch SSK, modified by
König-Fachsenfeld, the tail comes a high point. Mercedes had modified Merz's SSK differently, and the
Sindelfingen-made body of Merz's car curved down markedly at the rear, a configuration much more likely to create substantial lift. The characteristics of the accident, and the fact it happened in an untested vehicle, has led many experts, including
Karl Ludwigsen, to believe the aerodynamic configuration of Merz's car may have played an important role in this tragedy. == Personal life ==