The First Modern Automobile – The revolutionary 1902-1905 Mercedes-Simplex

Gary Anders with Michael Plag
David Gooley and Susan Morehouse
This 1903 Mercedes- Simplex has more in common with cars built today, over 100 years after it first left the Cannstatt factory, than it has with the horseless carriage – literally a four-wheel, two-seat open carriage with a 1-cylinder gasoline engine mounted in the rear – that Gottlieb Daimler and Wilhelm Maybach built in 1886. The number of innovations introduced during the first 15 years of the automotive age is almost unbelievable, particularly when we consider that they were entirely the inspiration of just three men: Daimler, Maybach and an enthusiastic Austrian by the name of Emil Jellinek.


The First Modern Automobile

The revolutionary 1902-1905 Mercedes-Simplex


Article Gary Anderson

Images David Gooley, Susan Morehouse, Gary Anderson, Daimler Global Media


When this 1903 Mercedes- Simplex drives down a modern street, we can see that it has more in common with cars built today, over 100 years after it first left the Cannstatt factory, than it has with the horseless carriage – literally a four-wheel, two-seat open carriage with a 1-cylinder gasoline engine mounted in the rear – that Gottlieb Daimler and Wilhelm Maybach built in 1886. The number of innovations introduced during the first 15 years of the automotive age is almost unbelievable, particularly when we consider that they were entirely the inspiration of just three men: Daimler, Maybach and an enthusiastic Austrian by the name of Emil Jellinek.

Jellinek, a car dealer in the south of France, sought to offer wealthy young clients the type of cars they truly desired. To do so, he worked closely with Daimler engineers to develop motorcars that would be fast enough to be more exciting than a horse and carriage, elegant enough to chauffeur the elite on social outings, and reliable enough to undertake the long journeys between their various homes – all proven and tested by success in racing events held at the resort retreats they frequented. In just a few years, Jellinek and his self-christened Mercedes cars would succeed handsomely.

It’s fascinating to take a walk around the Mercedes-Simplex with Michael Plag, head of prewar restoration at Mercedes-Benz Classic and caretaker of this vehicle for the past 35 years, as he points out the innovations that justify calling this car “the first modern automobile.” It’s even more enjoyable to observe as Plag demonstrates how to start the car and then takes us for a drive near the Pebble Beach Golf Club during the 2017 Monterey Classic Car Week.


Overall design

Spurred on by a desire for improved handling and stability, major advances from the horseless-carriage era were built into the Simplex’s design. The car was long relative to its height, with the engine in front of the passenger compartment rather than under or behind it. Mounting the chassis near the wheel centers instead of above them offered a lower center of gravity, thus allowing the machine to handle rough roads more comfortably and corner with less body roll.

Mounting the engine in front of the driver – and the radiator in front of the engine – vastly improved cooling. Maybach increased cooling further with a honeycomb radiator of his own design, providing significantly more cooling surface than his previous tubular design, which itself had been a major innovation just three years earlier, and paved the way to high-performance engines of more than 20 horsepower.

Early vehicles had either used a single front wheel steered by a direct tiller or two wheels on a single axle that pivoted at the center like a wagon, usually controlled by a tiller and chain drive. In 1893, Carl Benz was the first to build a gasoline-engined motorcar with the front wheels on separate pivots at the corners of the vehicle. A steering wheel and diagonal steering column connected to a steering arm made each wheel  follow the inner and outer curve around corners.

This innovation allowed for both better springing in front for greater comfort, and more modulated steering that was less prone to accidental movement from road ruts. Daimler soon adopted this design on his new cars.

Connecting the rear wheels to the driveshafts by chains allowed them to be separately sprung as well, improving both comfort and road handling.  

Maybach and Daimler also changed the seating so that passengers and drivers all faced forward. Though this seems like a small step forward from our modern perspective, it simplified body design and reduced the likelihood of motion sickness as driving speeds increased.

Maybach’s design allowed the body aft of the driver seat to be detachable, permitting the car to be configured as both a two-person racing machine and as a four- or five-passenger boulevard cruiser. Cabriolet or closed saloon body styles could also be fitted. It would be a simple step from here to transport and cargo vans a few years later.


Engine design

In the early days of the automobile, engine weight was a major obstacle to designing a self-propelled vehicle. Internal-combustion engines, although more efficient than steam engines, were quite heavy. Both the Daimler-Maybach team and Benz had made a start at overcoming this issue in their first vehicles, but more progress was needed. With redesigned engine components and newly enhanced fabrication methods, each successive engine conceived by Maybach had an improved power-to-weight ratio, as well as other advances coaxed from the evolving gasoline engine. By the time the first Mercedes appeared in 1901, engineers had moved from one to two and then to four cylinders.

Valves actuated by camshafts connected to the crankshaft controlled fuel-mixture intake and exhaust flow out of the cylinders. The 35HP Mercedes which used this system for the very first time had an open camshaft on each side of the engine, while the 40 HP evolution model – launched a year later and called Mercedes-Simplex for the first time – had enclosed camshafts. Using camshaft-controlled intake and exhaust allowed for smoother engine operation at higher engine speeds: This single innovation notably improved the overall motoring experience.

Ignition was by a so-called make-and-break system in which a spark was generated by closing and opening two contacts in an electrical circuit in which the low voltage was generated by magneto – built by Bosch even then. This complex system was nevertheless a major advance over previous open-flame and platinum hot-tube methods; it would itself soon be replaced by spark plugs, which have been retrofitted to the car seen here here to support higher speeds.

Similarly, the carburetion process had advanced from vapor carburetion to venturi carburetion with fuel flow from an internal reservoir with a float-actuated valve controlling the fuel level.

To cool the engine, the 1902 Mercedes-Simplex had vanes built into the flywheel – an improvement over the 35HP Mercedes of 1901 – which pulled air through the radiator and across the engine. In later models, this would be further enhanced by mounting a fan directly into the airflow between radiator and engine. With each advancement in cooling, the amount of water required for the cooling system could be reduced, further decreasing overall vehicle weight.


Power, transmission, brakes

A series of innovations were made in the way power was transferred from the engine to the driving wheels from the first vehicles to this Simplex. Adding gears to cope with different terrains, loads and road speeds within a relatively narrow engine-rpm range was the first advancement; by the time this Simplex was built, Daimler had also designed and installed a transmission with four forward and one reverse gears.

A clutch, actuated by a foot pedal, allowed the engine to freewheel when a new gear was being selected. Gear selection was done using a lever mounted on the steering column in the 1901 35 HP model. On the newer 40 HP machine of 1902, the gear lever was moved to the driver’s right and mounted on the same exterior pivot as the hand brake.

Braking was achieved by a hand brake with rods connected to brake pads pushing outward from within the rear wheel hubs for minor speed adjustments. When rapid retardation was required, two foot pedals would act directly on the driveshafts and crankshaft to slow the engine.

A throttle pedal on the right completed the series of control pedals, and the pattern of clutch pedal on the far left, with brake and then throttle pedal, would be adopted by most other automobile manufacturers.

Power was sent to the drive wheels from the transmission through a differential-gearing system connected to transmission, driveshafts and sprockets linked to the rear wheels with chains. Only later would a driveshaft able to handle the power be engineered to connect transmission and rear axles, finally doing away with chain drive.


The origin of this car

In spite of the significance of the 35HP Mercedes (only 29 of which were produced in 1901), no specimens are known to exist. The vehicle seen here is one of the rare 40HP Mercedes-Simplex models, which went into production in 1902 and continued to be built for three more years. It is one of two examples in the Mercedes-Benz Museum collection in Stuttgart. Company records show that a private owner in Germany purchased this particular example in early 1903. In the 1970s, it was discovered in Buenos Aires, Argentina, in rather poor condition. The Mercedes-Benz Classic Center acquired the car and completely restored it for Museum demonstration use.

Michael Plag of Mercedes-Benz Classic has cared for this 1903 Mercedes-Simplex 40 HP Tonneau for 35 years.



Designed by Wilhelm Maybach to parameters outlined by automotive visionary Emil Jellinek, this advanced machine had a wide body and a low center of gravity.


Multiple innovations in engine design, cooling, suspension, handling and braking vaulted the Simplex into a class of its own


Looking under the hood at the intake (top) and exhaust (bottom) sides of Wilhelm Maybach’s 4-cylinder, 40-horsepower masterpiece.


Cam-controlled intake and exhaust valves made operation quieter and smoother, and an improved carburetor allowed increased engine speeds.


This general engine template was employed to create increasingly powerful and successful racing and customer machines


Everything a gentleman needed to operate a modern motorcar was grouped on the Simplex’s dash. From the left are fuel- and oil-pressure pump and gauge, a twist-handle water-pump greaser, a bank of glass oil-level indicator tubes, with the round electrical ignition switch below, and glass oil reservoir and pump. The foot pedals are (from left) the clutch pedal, drive shaft and crankshaft brake pedals next to the steering column, and the round throttle pedal below.


The Mercedes-Simplex was aptly named, not only for the rational, reductionist nature of its mechanical design, but also for the simple and elegant details of its running gear and minimalist body devoid of unnecessary flourish.


With its low-slung stance and large radiator emblazoned with the single word “Mercedes,” the Simplex became a rolling worldwide advertisement for the quality, performance and advanced engineering of the new brand from Stuttgart known today as Mercedes-Benz.



1902-1905 Mercedes-Simplex 40HP

TYPE: Open roadster fitted with two-passenger rear body with rear-opening door

ENGINE: T-head 6.8-liter, 4-cylinder with dual-cam intake and exhaust valves

TRANSMISSION: 4-speed and reverse, aluminum case

HORSEPOWER: 40 horsepower at 1,050 rpm  

WHEELBASE: 122 in   CURB WEIGHT: 2,600 lb  

TOP SPEED: 50 mph



How to Start a Simplex

Michael Plag’s 15 Easy Steps

1. Pressurize fuel and oil tanks with lever on left of dash to move gasoline to carburetor and oil to engine.


2. Check glass tubes on dash to ensure all mechanical components of engine are correctly oiled.


3. Remove footboard to allow access to combination flywheel/engine fan.


4. Remove oil fitting plug on flywheel and oil the flywheel and clutch.


5. Oil valve guides on intake valves. The Simplex was the first car to have intake valves driven by camshaft.


6. Oil  the valve guides on the exhaust valves, which are driven by camshaft on exhaust side of the engine.


7. Open the valves at the tops of cylinders and inject high-octane starter fluid into each cylinder.


8. Depress float in the carburetor reservoir to start gasoline flowing into carburetor. There is no choke.


9. Adjust fuel mixture for conditions and retard spark timing for starting with control levers on steering wheel.


10. Give starter crank two turns to bring fuel up into cylinders. Never do this with ignition switch on


11. Switch on the ignition system via  the electrical switch on dashboard to allow ignition and combustion.


12. While the co-driver controls foot throttle, crank engine to start. First start of day may take multiple tries.


13. Next, move the ignition timing and fuel mixture levers back into their running positions.


14. Check oil levels in glass tubes and if necessary, pump additional pressure into the oil-feed lines.


15. Release hand brake, engage the clutch, shift into first gear, release the clutch and motor away.