The Karl Benz Patent Motorwagen (or motorcar), built in 1885, is widely regarded as the first automobile, that is, a vehicle designed to be propelled by a motor. The vehicle was awarded the German patent, number 37435, which Benz applied for on January 29, 1886. Following official procedures, the date of the application became the patent date for the invention once the patent was granted, which occurred in November of that year. Benz officially unveiled his invention to the public on July 3, 1886 on the Ringstrasse (Ringstra?e) in Mannheim, Germany. After developing a successful gasoline-powered two-stroke piston engine in 1873, Benz focused on developing a motorized vehicle while maintaining a career as a designer and manufacturer of stationary engines and their associated parts. The Benz Patent Motorwagen was a three-wheeled automobile with a rear-mounted engine. The vehicle contained many new inventions. It was constructed of steel tubing with woodwork panels. The steel-spoked wheels and solid rubber tires were Benz's own design. Steering was by way of a toothed rack that pivoted the unsprung front wheel. Fully-elliptic springs were used at the back along with a live axle and chain drive on both sides. A simple belt system served as a single-speed transmission, varying torque between an open disc and drive disc. Karl Benz - detail from gravestone Working replica of the 1885 Benz Motorwagen in Frankfurt, 2007 The first Motorwagen used the Benz 954 cc single-cylinder four-stroke engine. This new engine produced ? hp (? kW) at 250 rpm in the Patent Motorwagen, although later tests by the University of Mannheim showed it to be capable of .9 hp (0.7 kW) at 400 rpm. It was an extremely light engine for the time, weighing about 100 kg (220 lb). Although its open crankcase and drip oiling system would be alien to a modern mechanic, its use of a pushrod-operated poppet valve for exhaust would be quite familiar. A large horizontal flywheel stabilized the single-cylinder engine's power output. An evaporative carburettor was controlled by a sleeve valve to regulate power and engine speed. Bertha Benz, the wife of the inventor, chose to publicize the Patent Motorwagen in a unique manner—she took the Patent Motorwagen No. 3, supposedly without her husband's knowledge, and drove it on the first long-distance automobile trip to demonstrate its feasibility as a means to travel long distances. That trip occurred in early August 1888, when Bertha Benz drove with her sons Eugen and Richard (fifteen and fourteen years old) from Mannheim through Heidelberg, and Wiesloch, to her hometown of Pforzheim. As well as being the driver, she acted as mechanic on the drive, cleaning the carburetor (the first model of the Motorwagen had not been built with a carburetor, rather a basin of fuel soaked fibers that supplied fuel to the cylinder by evaporation) with her hat pin and using a garter to insulate a wire. She refueled at the local pharmacy in Wiesloch and replaced the brake lining several times along the journey. After sending a telegraph message to her husband of her arrival in Pforzheim, she spent the night at the home of her mother and returned home three days later. The trip covered 194 km (120 mi) in total. In Germany, a parade of antique automobiles celebrates this historic trip of Bertha Benz every two years. In 2008, the Bertha Benz Memorial Route[1] was officially approved as a route of industrial heritage of mankind, because it follows Bertha Benz's tracks of the world's first long-distance journey by automobile in 1888. Now everybody can follow the 194 km (121 mi) of signposted route from Mannheim via Heidelberg to Pforzheim (Black Forest) and back.