A step towards the modern hybrid drive system were the early experiments of Wilhelm Maybach in engine development, which sought to optimize the existing gasoline engine by combining it with alternative drive technologies. In 1902 he patented a two-cylinder engine which was supposed to combine the functions of the internal combustion engine and the steam engine. But especially his “vehicle drive system consisting of an internal combustion engine and a pneumatic engine,” patented on January 29, 1905, was intended to eliminate design drawbacks of the internal combustion engine.

It provided for a compressor driven by a gasoline engine. The compressed air thus obtained was additionally heated by the exhaust gas to raise the compression level. Two pneumatic engines, horizontally opposed units arranged beneath the body, converted the pressure into kinetic energy to drive the wheels. With this unconventional engine, Maybach wished to get higher torque for starting off (among other things). Above all, however, the system, a serial hybrid drive system, was intended to eliminate heavy engine parts: as an advantage of his engine, the design engineer emphasized the “elimination of the toothed wheel drive, the differential, the clutch and the brakes on the gearbox, i.e., the elimination of parts which previously gave rise to complaints.” Also, the drive system was said to be very easy to operate. However, high cost and poor efficiency spoke against putting the patent into practice.

The first hybrid vehicle of the Mercedes brand originated in Vienna. As early as in 1906, the Viennese edition of Allgemeine Automobil-Zeitung (AAZ) announced the launch of the Mercedes Mixte for the next year. In 1907 the car drew an even bigger response from the trade press: “The >Mixte< is the Mercedes company’s special new product of the season,” AAZ wrote, recommending it for the “mature motorist who looks forward to new sensations in motoring with the mixed car.”

The Austrian affiliate of Daimler-Motoren-Gesellschaft, which built the electric and hybrid vehicles of the Mercedes brand, originated in 1899 as “ Österreichische Daimler Motoren Commanditgesellschaft Bierenz Fischer & Co.” Initially, Paul Daimler, Gottlieb Daimler’s eldest son, took over as Chief Engineer. On July 19, 1906, the Austrian engineer Ferdinand Porsche was appointed Chief Engineer. Porsche already had designed an electric motor for wheel hub installation in 1897. This system was fitted for the first time in the Lohner-Porsche of 1900. This car was created in the workshops of the “imperial and royal car factory” of Jacob Lohner & Co. in Vienna, for which Porsche started working in 1898. In 1900 the new car made a big splash at the Paris World Exposition.

The engineering of the Mixte vehicle relied on the Lohner-Porsche system. Ferdinand Porsche, Chief Engineer of Daimler-Motoren-Gesellschaft since 1906, had further improved a development of his own and combined it with an internal combustion engine for the Mercedes Mixte. AAZ had already described a Porsche-built forerunner of the Mercedes Mixte in 1902. The “ Mercedes-Lohner-Porsche” was manufactured by Lohner with different outputs for the Mercedes engine. The racing car built in 1902 using a 28-hp (21-kW) engine from the Mercedes Simplex could make do entirely without a battery as buffer unit owing to the high output of the gasoline engine.

A contemporary report described the design of the serial hybrid drive system of the Mercedes Mixte: “The motive power is supplied by a gasoline engine, which entirely corresponds to the engines used in the gasoline car. Coupled with the gasoline engine is a dynamo that converts the energy of the gasoline engine into electric energy to supply power to two traction motors which, like the electric motors, are designed as wheel motors.”

The gasoline engines used were mainly the 45 and 70 hp (33 - 52 kW) units. The model designations of the Mercedes Mixte referred to the internal combustion engines, not the output of the electric drive. A six-pole dynamo was permanently coupled to the engine by means of a drive shaft and took over the function of the flywheel. The magnet cluster around which the armature of the dynamo rotated was not rigidly installed, but could be moved 20 millimeters. This permitted regulating the current when the tractive power had to be changed. The dynamo took over the function of the flywheel – quite similar to several modern-day hybrid drive systems. In some cars it served as a starter motor for the internal combustion engine. The electric energy produced by the generator was transmitted to two wheel hub motors. The spokes were attached to the armature housing of the wheel hub motor – motor and wheel formed a unit, reducing energy losses which the friction of mechanical power transmission would have caused.

In the Mercedes Mixte the motors were positioned on the rear axle. A few fire-fighting vehicles were delivered with front-wheel drive, as was standard on the Lohner-Porsche. Although Ferdinand Porsche made the motors, which ran on two ball bearings, appreciably narrower than the traction motors of his first electric automobiles, the Mercedes Mixte and Mercedes Electrique easily could be recognized by their unusual hubs. Reporters at the Vienna motor show in 1907 pondered over the aesthetics: on the one hand, they expressed their admiration for the established “mature beauty of the Mercedes cars,” but now there was this “dumpling”, the wheel hub motors on the rear wheels.

The combination of internal combustion engine as source of power and electric motor as drive proper particularly proved itself in buses. The gentle acceleration of the vehicles and the lack of heavily stressed components like clutch and transmission recalled the advantages of electric cars. In continuous operation, however, the Mixte was superior to the electric car owing to the large range lent to it by the gasoline engine coupled with a generator. To demonstrate the performance of the series, Porsche developed a Mixte racecar before the end of 1907. The car’s generator was powered by a 30/55-hp gasoline engine; wheel hub motors with enhanced power input transferred the electric energy to the road. The hybrid racer was supposed to start in the Taunus Race, but skidded off the track during tests and was severely damaged.

In 1912 the Austrian Daimler-Motoren-Gesellschaft dissolved its ties with the parent company in Germany. The company, located in Vienna’s Neustadt district, was renamed “Austro-Daimler Motoren AG,” and Ferdinand Porsche remained its Chief Engineer until 1923. Owing to the rapid succession of innovations in automobiles with gasoline engines, the interest in hybrid vehicles quickly subsided in the first quarter of the last century. For several decades this technology ceased to play a prominent role in the development of the automobile.