Rennzweier (The Double Racer) is a veteran automobile manufactured by Nesselsdorfer Wagenbau-Fabriks-Gesellschaft A.G. (now known as Tatra) in 1900. It is sometimes called also as First racing, 12 HP or Rennwagen (The Race Car). It was manufactured on order of baron Theodor von Liebig. Also Hans Ledwinka, at the time only 20 years old, was taking part in construction of the car, later to become the most important Tatra designer. The car was manufactured on May 5, 1900, and the manufacture process took only 5 weeks.
The construction was unique at the time. The car was very low, especially the drivers seat. There was no carrossery - all mechanical parts were uncovered. Unlike its predecessors, the steering column was slightly tilted.
The car had modified Benz engine. It was two cylinders spark ignition engine with power output of about 9 kW (12HP) at 1800RPM. It was situated above the driven rear axle, long-wise with the cars axis.
The driver was situated on heightened seat behind the steering wheel, while the passenger's seat was much lower on the frame, so his legs were sticking out under the car.
The gas tank had volume of 42 liters, while there was also another tank behind the driver for 15 liters of coolant.
The car was able to reach maximum speed of 82 km/h.
Von Liebig raced the car in numerous contests. He won the race Nice - La Turbie, and took second position in Salzburg-Linz-Vienna race. He later took part also in Paris-Vienna race.
Today the Rennzweier is in the Czech National Technical Museum.
Second racing car was made in 1901. It was again without carrossery, and this time a Hardy engine (flat two, 3188cc, 7,4 kW-8,85 kW (10-12HP)) was used instead of the previous Benz one.
In 1899, the NW-cars Wien and Nesselsdorf (descendant models after the Präsident), achieved their first significant racing success on the trotter course in Vienna Prater. It was the first race in Austrian monarchy at all - started on October 23, 1899. The driver of the winning NW-car Wien was baron Theodor von Liebig. The other NW-car Nesselsdorf was the second one before all concurrent of four Benz-cars and four Dietrich-Bolleé cars. Later in March 1900 Liebig raced the triangle 192 km track Nizza - Draguignan - Nizza, where he won the second stage at all. Four days later he won the class of four-seaters up to 1000 kg in famous hill climb race Nizza - La Turbié. Based on this achievements, baron Liebig ordered a construction of a new automobile. While the previous cars Liebig used in races were built as common cars, the one he ordered was to be designed purposely as a race car.