Mercedes-Benz
300 Convertible D (W 186)

Why it matters

The 300 Convertible D (W 186 II) is the first-series four-door cabriolet of the 300 "Adenauer" line and the most numerous of the open versions, with 455 built between 1952 and 1954 according to the factory archive. RM Sotheby's describes the Cabriolet D as built to the standard of the pre-war 500 K and 540 K, with a landau-bar cabriolet top, a six-seat leather interior and trim of chrome-plated brass and hardwood.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

Photos

Exterior, interior and detail photos with their licences.

• Mercedes-Benz 300 Convertible D (W 186) (Wikimedia Commons search)
  Photo: Ermell · CC BY-SA 4.0
• Mercedes-Benz 300 Convertible D (W 186) (Wikimedia Commons search)
  Photo: Ermell · CC BY-SA 4.0
• Mercedes-Benz 300 Convertible D (W 186) (Wikimedia Commons search)
  Photo: Ermell · CC BY-SA 4.0

Production

Every figure says what it counts.

Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.

History

The 300 was shown at Frankfurt in April 1951. The archive gives pre-production from April 1951 and standard production from March 1952 to April 1954. The engine delivered 115 hp at 4600 rpm. Early changes during the run were a fuel tank enlarged from 65 to 72 litres from February 1952 and recirculating-ball steering replacing worm-and-lever in 1952. The price was DM 21,600 without tyres in March 1951 and DM 23,700 including tyres in February 1952.

RM Sotheby's states that only 591 Cabriolet Ds were hand-built to order between late 1951 and summer 1955, a figure that matches the archive counts of 455 for this series plus 136 for the 300 b. A Monterey 2024 catalogue entry documents a US-market car built on 31 December 1952 in dark green with a Becker Nürburg III radio, and Bonhams offered a 1952 car with chassis number 18601401640/52.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Identification guide

How to tell an original from a replica or later conversion.

The factory type is 186.014 (design name W 186 II). The engine is the M 186 I (186.920), 2996 cc, 115 hp at 4600 rpm, compression ratio 6.4, with two Solex 40 PBJC downdraught carburettors. The gearbox is a four-speed manual with ratios 3.68, 2.25, 1.42 and 1.0 and a final drive of 4.44. Early cars have worm-and-lever steering, changing to recirculating-ball in 1952. Tyres are 7.00-15 extra on 5 K x 15 rims. At 4950 mm the car is shorter than the later 300 b and 300 c (5055 mm), and its height is 1640 mm. Auction catalogues show chassis numbers of the form 186.014.02905/52 and 18601401640/52, i.e. type code, serial number and model-year suffix.

Sources

Each number links to the exact facts it supports.

1. 1
   300 Convertible D / W 186 II, 1952 - 1954 Level A Mercedes-Benz Public Archive (Classic M@RS)

   • Units produced : 455
   • Engine type : M 186 I / 186.920 (Specifications)
   • Number of cylinders / arrangement : 6 / in-line (Specifications)
   • Total displacement : 2996 cc (tax classification: 2975 cc) (Specifications)
   • Bore x Stroke : 85 x 88 mm (Specifications)
   • Compression ratio : 6.4 (Specifications)
   • Valve operation : 1 overhead camshaft (Specifications)
   • Fuel system : 2 Solex 40 PBJC downdraught carburettors (Specifications)
   • Rated output : 115 hp at 4600 rpm (Specifications)
   • Rated torque : 20 mkg at 2500 rpm (Specifications)
   • Gearing : 4-speed manual transmission (Specifications)
   • Gear ratios : I. 3.68; II. 2.25; III. 1.42; IV. 1.0; R. 3.08 (Specifications)
   • Final drive ratio : 4.44 (Specifications)
   • Driven wheels : rear wheels (Specifications)
   • Frame design : cruciform oval-tube frame with centre reinforcement / steel unit body (Specifications)
   • Front-wheel suspension : double wishbone (Specifications)
   • Rear-wheel suspension : swing axle (Specifications)
   • Brake system (foot brake) : hydraulic, acting on front- and rear wheels; four-wheel drum brakes (Specifications)
   • Steering : worm-and-lever steering, from 1952 recirculating-ball steering (Specifications)
   • Wheelbase : 3050 mm (Specifications)
   • Length : 4950 mm (Specifications)
   • Width : 1838 mm (Specifications)
   • Height : 1640 mm (Specifications)
   • Front / rear track : 1480 / 1525 mm (Specifications)
   • Kerb weight : 1820 kg (Specifications)
   • Maximum speed : 155 km/h (Specifications)
   • Acceleration 0-100 km/h : 18 s (Specifications)
   • Fuel tank: position / capacity : in the rear / 65 l; from 02.1952: 72 (Specifications)
   • Fuel consumption : 13.8 l (Specifications)

   Accessed 2026-11-12
2. 2
   Mercedes-Benz Classic M@RS archive – 300 Convertible D Level A

   • 455 Convertible D

   Accessed 2026-11-12