This one was even faster. In 1938 already, on the same autobahn. On 28 January 1938, Caracciola and the Mercedes-Benz record team appeared on the Reichs-Autobahn A5 between Frankfurt and Darmstadt, in an attempt to break numerous speed records set by the Auto Union team.[87] The system of speed records at the time used classes based on engine capacity, allowing modified Grand Prix cars, in this case a W125, to be used to break records. Caracciola had broken previous records—he reached 311.985 kilometres per hour (193.858 mph) in 1935—but these had been superseded by Auto Union drivers, first Stuck and then Rosemeyer.[88] Driving a Mercedes-Benz W125 Rekordwagen, essentially a W125 with streamlined bodywork and a larger engine, Caracciola set a new average speed of 432.7 kilometres per hour (268.9 mph) for the flying kilometre and 432.4 kilometres per hour (268.7 mph) for the flying mile, speeds which remain to this day as some of the fastest ever achieved on public roads.