Rare Car Archive

Makes › Mercedes-Benz Germany › 300 › 300 c Convertible D (W 186) · Rare specification · 1955–1956 Extremely Rare

Mercedes-Benz
300 c Convertible D (W 186)

Four-door Cabriolet D of the 300 c.

IDENTIFICATION CARD · MERCEDES-BENZ 300 C CONVERTIBLE D (W 186) 1955–1956
No licensed photograph yet. Photographs are published only when their licence permits it.
51BuiltFactory reported
0Chassis documentedin this archive
?SurvivingNot yet verified
Contents
  1. 01Overview
  2. 02Production & history
  3. 03Specifications
  4. 04Colours & options
  5. 05Individual cars
  6. 06Reference

01Overview

At a glance

Built
51 Built
Years
1955–1956
Engine
front-mounted, longitudinal inline six · 2,996 cc / 3.0 LFactory: 2,996 cc
Power
93.2 kW / 127 PSFactory: 125 hp · converted
Top speed
160 km/hFactory: 160 km/h
Body
Not yet verified
Designer
Not yet verified
In this archive
Not yet verified
Surviving
Not yet verified

Sources and any conflicting figures are in the sections below.

Why it matters

The 300 c Convertible D was the last four-door open Mercedes-Benz 300 of the first generation. It appeared at the 1955 Frankfurt show, could be ordered with Mercedes-Benz's first automatic gearbox, and was dropped after roughly nine months because demand was low. The factory archive counts 51 units.

How rare is it?

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

Model rarityNot yet assessed
Specification rarityExtremely Rare 51 · Built1,2
Colour rarityNot yet assessed
Individual rarityNot yet assessed
Historical rarityNot yet assessed
Survival rarityNot yet assessed

Each kind of rarity is rated separately and never combined.

02Production & history

Production

Every figure says what it counts.

What is countedFigureBasisStatus
Factory package productionConvertible D 511,2 Factory production Factory reported

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 c was shown at the third Frankfurt motor show in September 1955. It was recognisable by a larger rear window and broader tyres, and it received the single-joint swing axle already used on the 180 and 180 D. An optional three-speed automatic gearbox, built to a Borg-Warner design as the "Detroit-Gear", was offered for the first time. To unify production, and because demand was low, the convertible left the sales programme in April 1956 and was built until June 1956. In September 1955 it was priced at DM 24,700 with the manual gearbox and DM 26,200 with the automatic.

RM Sotheby's offered a car from a private collection in 2026 and writes that only 51 examples of the 300 c are believed to have been built as Convertible D, in line with the factory figure. A catalogue text for another car gives 1,432 units for the whole 300 c range built from September 1955 to June 1957.

Variants

How each version differs from the standard 300 c Convertible D (W 186).

No variants documented yet. Have a source? Contribute it.

03Specifications

Technical specifications

Engine

Engine familyNot yet verified
Engine codeM 186 II / 186.920, with automatic transmission: 186.9211
Layoutfront-mounted, longitudinal inline six1Source: Configuration "front, longitudinal; vertical"; cylinders "6 / in-line".
Cylinders61
Displacement 2,996 cc / 3.0 LFactory: 2,996 cc1Tax classification: 2975 cc.
Bore 85 mmFactory: 85 mm1
Stroke 88 mmFactory: 88 mm1
Compression ratio7.4 - 7/51Value as printed in the source.
Valvetrain1 overhead camshaft; camshaft drive: double roller chain1
Fuel system2 Solex 32 PAIAT compound downdraught carburettors with automatic choke1
Power 93.2 kW / 127 PSFactory: 125 hp · converted1Rating: manufacturer
Power at 4,500 rpm1
Torque 221 Nm / 22.5 kgmFactory: 22.5 kgm1Source unit is "mkg".
Torque at 2,600 rpm1

Transmission & drivetrain

Gearbox4-speed manual transmission (change-speed gear)1
Gears41
Gear ratiosI. 3.44; II. 2.30; III. 1.53; IV. 1.0; R. 3.081
Final drive4.671
Driven wheelsrear wheels1

Chassis, body & dimensions

Chassiscruciform oval-tube frame with centre reinforcement1
Front suspensiondouble wishbone; coil springs, torsion bar stabiliser1
Rear suspensionsingle-joint swing axle; double coil springs, electrically engageable torsion-bar suspension1
Brakeshydraulic, with vacuum booster, acting on front- and rear wheels; four-wheel drum brakes1
Steeringrecirculating-ball steering1
Body constructionsteel unit body1
Wheelbase 3,050 mmFactory: 3,050 mm1
Length 5,055 mmFactory: 5,055 mm1
Width 1,838 mmFactory: 1,838 mm1
Height 1,600 mmFactory: 1,600 mm1
Front track 1,480 mmFactory: 1,480 mm1
Rear track 1,525 mmFactory: 1,525 mm1
Kerb weight 1,940 kgFactory: 1,940 kg1DIN 70020: ready to drive, including fuel, spare wheel and tool kit. Source gives: 1940 kg, with automatic transmission 1990 kg
Dry weightNot yet verified

Performance

Maximum speed 160 km/hFactory: 160 km/h1
0–100 km/h 17 s1
Fuel tank 72 LFactory: 72 L1
Fuel consumption 12.5 L/100kmFactory: 12.5 L/100km1Mercedes-Benz archive figure in litres per 100 km: 12.5 l (DIN 70030: at 3/4 of top speed, not more than 110 km/h, plus 10 %)

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

04Colours & options

Factory colours & interiors

Original paint and trim, with the number of cars in each where a source gives it.

Not yet documented. Have a source? Contribute it.

Factory options & codes

Codes are shown exactly as written by the manufacturer.

Not yet documented. Have a source? Contribute it.

05Individual cars

Chassis register

Every documented car, with its colours, history and where it is now. Open a row for the full record. Known chassis are not automatically authenticated originals.

Not yet documented. Have a source? Contribute it.

Competition history

Every race result of the individual cars, in date order. Click a chassis number to open its full record in the register.

Not yet documented. Have a source? Contribute it.

Auction & sale history

Documented public sales of the individual cars. Click a chassis number to open its full record in the register.

Not yet documented. Have a source? Contribute it.

See one in person

Museums where an example of this car can be seen.

No example is documented on public display yet. Have a source? Contribute it.

06Reference

Identification guide

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

The factory type is 186.033 (design name W 186 IV). The engine is the M 186 II (186.920), or 186.921 when combined with the automatic gearbox: 2996 cc, 125 hp at 4500 rpm. The rear axle is a single-joint swing axle, whereas the 300 b has the plain swing axle. Wheels are 5 1/2 K x 15 rims with 7.60 S 15 tyres, and the height is 1600 mm against 1640 mm on the 300 b. A 3-speed automatic gearbox with steering-column selector was optional; the standard gearbox is the four-speed manual.

Sources

Each number links to the exact facts it supports.

  1. 1
    300 c Convertible D / W 186 IV, 1955 - 1956 Level A Mercedes-Benz Public Archive (Classic M@RS)
    • Units produced : 51
    • Engine type : M 186 II / 186.920, with automatic transmission: 186.921 (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 : 7.4 - 7/5 (Specifications)
    • Valve operation : 1 overhead camshaft (Specifications)
    • Fuel system : 2 Solex 32 PAIAT compound downdraught carburettors with automatic choke (Specifications)
    • Rated output : 125 hp at 4500 rpm (Specifications)
    • Rated torque : 22.5 mkg at 2600 rpm (Specifications)
    • Gearing : 4-speed manual transmission (Specifications)
    • Gear ratios : I. 3.44; II. 2.30; III. 1.53; IV. 1.0; R. 3.08 (Specifications)
    • Final drive ratio : 4.67 (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 : single-joint swing axle (Specifications)
    • Brake system (foot brake) : hydraulic, with vacuum booster, acting on front- and rear wheels; (Specifications)
    • Steering : recirculating-ball steering (Specifications)
    • Wheelbase : 3050 mm (Specifications)
    • Length : 5055 mm (Specifications)
    • Width : 1838 mm (Specifications)
    • Height : 1600 mm (Specifications)
    • Front / rear track : 1480 / 1525 mm (Specifications)
    • Kerb weight : 1940 kg, with automatic transmission 1990 kg (Specifications)
    • Maximum speed : 160 km/h (Specifications)
    • Acceleration 0-100 km/h : 17 s (Specifications)
    • Fuel tank: position / capacity : in the rear / 72 l (Specifications)
    • Fuel consumption : 12.5 l (Specifications)
    Accessed 2026-11-12
  2. 2
    Mercedes-Benz Classic M@RS archive – 300 c Convertible D Level A
    • 51 Convertible D
    Accessed 2026-11-12

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