Mercedes-Benz W189

300d

A successor to Mercedes' flagship W186 series final model, the 300c, the enlarged 300d (W189) was introduced in August 1957. Its new chassis code reflected sweeping refinements that included modernized bodywork, pioneering fuel injection, and a unique hardtop configuration transforming it into a pillarless phaeton.

Available as both a saloon and cabriolet, it retained the W186's proven X-frame chassis and was fitted with a more powerful version of its 3.0 L (2996 cc/182 in³) overhead cam, aluminum head M186 straight-6, the M189.

This shared improvements proven in the iconic 300SL "Gull Wing", the fastest production car of its day, including Bosch mechanical direct injection and an innovative diagonal head-to-block joint that allowed for oversized intake and exhaust valves. Output was an even horsepower per cubic inch, 180 PS at 5500 rpm.

Designed to give reliable service under prolonged hard use, the engine featured deep water jackets, thermostatically controlled oil cooling, copper-lead bearings and a hardened crankshaft. A 3-speed Borg-Warner automatic transmission was standard. With no natural cruising speed, the car could sustain anything up to its maximum speed all day, road conditions permitting.

The combination of a rigid X-shaped ovoid steel tube frame and four-wheel independent suspension provided surprisingly nimble handling. Double wishbones, coil springs, and a stabilizer bar were used up front, and Mercedes' typical double coil spring swing axle in rear. An innovative dashboard-operated rear load-leveling suspension engaged a torsion bar to increase stiffness by one-third when needed, and a pedal-operated central lubrication system kept friction points silent. Brakes were vacuum-assisted hydraulic drum all around, steering recirculating ball. Power steering and Artic-Kar air-conditioning were new options.

An additional 4 inches of wheelbase provided greater rear legroom, equaling that of the long wheelbase model Rolls-Royce Silver Cloud also introduced that year. Removable rear quarter lights allowed an unobstructed view in and out from the front vent window on back, much valued in the model's popular role as a "parade car".

In addition to the saloon and cabriolet, three special "Pullman" variants were produced, with the wheelbase (and length) extended a further 450 mm - one was a standard limousine and the other two were landaulets. One of the landaulets was the Popemobile - it had its rear seat replaced with one custom armchair and was presented to Pope John XXIII in December 1960. The other landaulet and the limousine remained in Mercedes-Benz's ownership and were rented out to the government.

A total of 3,077 300d models (priced at DM 27,000) was produced through March 1962, along with 65 special-order 300d-based Cabriolet Ds (DM 35,500). After some overlap with the smaller, more contemporary styled W112 chassied 300SE "Fintail" sedan that shared its engine, the 300d limousine was ultimately replaced as company flagship by the 600 Großer Mercedes in 1963.

References

Notes

Bibliography

References

1. [http://storm.oldcarmanualproject.com/mercedes300d1958.htm Sales brochure for the Mercedes-Benz Type 300d, storm.oldcarmanualproject.com] Retrieved 23 August 2016
2. (September 2017). "Mercedes Benz 300 {{!}} Buy & Sell {{!}} Beverly Hills Car Club".
3. Jeff Miller. (2002-03-02). "Mercedes-Benz Type 300 "Adenauer" limousine © www.mbzponton.org". Mbzponton.org.
4. "300 300b 300c 300d Convertible Sedan 1951-1962". Silverstarrestorations.com.
5. (2 March 1967). "Used cars on test: Rolls Royce Silver Cloud". [[Autocar (magazine).
6. "300 - 300 d (W 186, W 189), 1951 - 1962".
7. "300 d special version with long wheelbase".