Gasoline/benzene as well as diesel motors had certainly been discovered long before, but truly mature application of them in rail service had to wait until the end of the Twenties / beginning of the Thirties, whereby many missteps were made. The engineer Franz Kruckenberg, a former airship builder, and Curt Stedefeld came close to the goal. By 1930, they had put together a fast propeller powered rail car with the nickname "Rail Zeppelin" in Hannover. This silver-painted vehicle with an intentional similarity to a Zeppelin on rails ran on only two single-axle sets of running gear. Its rear was flattened for streamlining and the most remarkable thing to strike the observer about it was the large, double-blade propeller on its upper area, which was driven by a twelve-cylinder aircraft motor from BMW with 600 horsepower, mounted on the rear. An astonishing advantage when in operation was that the propeller allowed smooth and thereby ideal speed control by simply stepping on the gas. Since there was no gearbox or other weight, it was possible to build the 25.85 meter / 84 foot unit using lightweight methods. It only weighed 18.6 metric tons and accommodated 40 people. After the first test runs in the Hannover area, Kruckenberg wanted to test this propeller car once on a longer line in fast service. He thus stood ready in the early morning hours of June 21, 1931 in Hamburg-Bergedorf around 3:27 AM for the departure to Berlin. The route between Hamburg and Berlin was considered in 1931 by the DRG as one of the fastest lines, since it had a mostly straight course and hardly any grades worth mentioning. After the departure, the speedometer dial quickly swung between 150 to 180 km/h / 94 to 113 mph on the open stretch of track. Soon, the 200 km/h / 125 mph mark was also passed and over a distance of about twelve kilometers, the car raced between Karstädt and Dergenthin at the peak of 230.2 km/h / 144 mph! This was a record! At around 5:05 AM after a running time of 1 hour, 38 minutes and 19 seconds, it finally rolled up to the platform at the Spandau West station. The "Berliner Tageblatt" newspaper then observed, "Rail Zepp faster than an airplane, Hamburg – Berlin in 102 minutes". In any event, the average speed of this record run at 157.3 km/h / 98 mph was impressive. Starting in August of 1932, this experimental vehicle was completely rebuilt, because it quickly became apparent that the propeller drive was not usable on a conventional railroad network. The BMW motor was now moved to the front of the vehicle and there it was geared to a freshly installed two-axle truck using a Föttinger System hydraulic transmission for forward and reverse running. Several experimental runs were done with the hydraulic transmission after the vehicle had been sold to the DRG in November of 1934. The vehicle then remained in storage and it was scrapped in the spring of 1939 without further ado.