Makes › Mercedes-Benz › 540 › 540 K Spezial-Roadster (Sindelfingen) · Rare production · 1936–1939 Ultra Rare

Mercedes-Benz
540 K Spezial-Roadster (Sindelfingen)

Factory Sindelfingen long-tail Spezial-Roadster body on the 540 K chassis – 25 of 419 chassis

25BuiltIndependently researched

0Chassis documentedin this archive

3SurvivingIndependently researched

Contents

01Overview
02Production & history
03Specifications
- Technical specifications
04Colours & options
- Factory colours & interiors
- Factory options & codes
05Individual cars
06Reference

01Overview

At a glance

Built: 25 Built
Years: 1936–1939
Engine: Supercharged OHV inline eight (Roots-type, driver-engaged) · 5,401 cc / 5.4 LFactory: 5,401 cc
Power: 134 kW / 182 PSFactory: 180 hp · converted
Top speed: 170 km/hFactory: 170 km/h
Body: Not yet verified
Designer: Hermann Ahrens (Sindelfingen)
In this archive: Not yet verified
Surviving: 3 (independently researched)

Sources and any conflicting figures are in the sections below.

Why it matters

The long-tail Spezial-Roadster is regarded as the ultimate form of the 540 K, itself one of the outstanding cars of the 1930s. Only 25 of the 419 540 K chassis carried this Sindelfingen coachwork.

How rare is it?

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

Model rarityUltra Rare 25 · Built¹

Specification rarityNot yet assessed

Colour rarityNot yet assessed

Individual rarityNot yet assessed

Historical rarityNot yet assessed

Survival rarityNot yet assessed 3 · Surviving²

Each kind of rarity is rated separately and never combined.

02Production & history

Production

Every figure says what it counts.

What is counted	Figure	Basis	Status
Total model productionoriginal long-tail, high-door Special Roadsters with covered spare wheel (a sub-type of the 540 K Special Roadster), per RM Sotheby's (2022)	3²	Surviving examples	Independently researched
Total model production540 K chassis carrying long-tail Spezial-Roadster coachwork (of 419 540 K chassis)	25¹	Factory production	Independently researched

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

History

The 540 K succeeded the 500 K during 1936, continuing a line that began with the 380 of 1933; together these models made up less than one percent of Mercedes-Benz output. The Spezial-Roadster was built by the company's own special-vehicle department at Sindelfingen and cost 28,000 Reichsmark. In all, 419 540 K chassis were built.

Variants

How each version differs from the standard 540 K Spezial-Roadster (Sindelfingen).

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

03Specifications

Technical specifications

Engine

Engine family	Not yet verified
Engine code	M 24 II³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Layout	Supercharged OHV inline eight (Roots-type, driver-engaged)⁴ Independently researched
Cylinders	8³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Displacement	5,401 cc / 5.4 LFactory: 5,401 cc⁴ Independently researched
Bore	88 mmFactory: 88 mm³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Stroke	111 mmFactory: 111 mm³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Compression ratio	5.2:1 (depending on fuel, up to 6.5:1)³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Valvetrain	1 intake and 1 exhaust valve per cylinder, overhead; 1 lateral camshaft driven via spur gears³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Fuel system	1 Mercedes-Benz twin updraught carburettor³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Induction	Engageable Roots supercharger³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Power	134 kW / 182 PSFactory: 180 hp · converted³Rating: manufacturerSupercharged rating; 115 hp without supercharger. Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Power at	3,400 rpm³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Torque	431 Nm / 44 kgmFactory: 44 kgm³The archive writes the unit as mkg (metre-kilograms). Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Torque at	2,200 rpm³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.

Transmission & drivetrain

Gearbox	Four-speed, synchromesh on third, dog clutch on fourth⁴ Independently researched
Gears	4³The 5-speed has ratios I. 3.90; II. 2.88; III. 1.45; IV. 1.0; V. 0.80 and final drive 3.50. Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Gear ratios	4-speed: I: 3.90; II: 2.88; III: 1.45; IV: 1.0³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Final drive	3.08 or 3.60 (4-speed)³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Driven wheels	Rear wheels³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.

Chassis, body & dimensions

Chassis	Box-section pressed-steel low-bed frame³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Front suspension	Double wishbone with coil springs³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Rear suspension	Swing axle with double coil springs; additional compensating springs up to 1938³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Brakes	Hydraulic with Bosch-Dewandre vacuum booster on front and rear wheels; mechanical parking brake on rear wheels³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Steering	Worm-and-nut steering³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Body construction	Not yet verified
Wheelbase	3,290 mmFactory: 3,290 mm³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Length	Not yet verified
Width	Not yet verified
Height	Not yet verified
Front track	Not yet verified
Rear track	Not yet verified
Kerb weight	Not yet verified
Dry weight	Not yet verified

Performance

Maximum speed	170 km/hFactory: 170 km/h³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
0–100 km/h	Not yet verified
Fuel tank	110 LFactory: 110 L³Base 540 K (W 29) chassis figure from the factory archive, not specific to this body.
Fuel consumption	29 L/100kmFactory: 29 L/100km³Mercedes-Benz archive figure in litres per 100 km: 29 l

“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.

Being verified against factory or registry sources before it is published. Have a source? Contribute it.

Sources

Each number links to the exact facts it supports.

1
RM Sotheby's Monterey 2011, lot 117: 1937 Mercedes-Benz 540 K Spezial Roadster by Sindelfingen Level C
- 25 540 K chassis carrying long-tail Spezial-Roadster coachwork (of 419 540 K chassis)
Accessed 2026-11-11
2
1937 Mercedes-Benz 540 K Special Roadster by Sindelfingen, Monterey 2022 Level C RM Sotheby's
- Just three original examples of this most sought-after design remain extant
Accessed 2026-11-12
3
540 K / W 29, 1936 - 1939 Level A Mercedes-Benz Public Archive (Classic M@RS)
- Engine type : M 24 II (Specifications)
- Number of cylinders / arrangement : 8 / in line (Specifications)
- Bore x Stroke : 88 x 111 mm (Specifications)
- Compression ratio : 5.2; depending on fuel, up to 6.5 (Specifications)
- Valve operation : 1 lateral camshaft; Camshaft drive : via spur gears (Specifications)
- Fuel system : 1 twin updraught carburettor Mercedes-Benz (Specifications)
- carburettor engine with engageable Roots supercharger (Specifications)
- Rated output : 115 hp, with supercharger 180 hp at 3400 rpm (Specifications)
- with supercharger 180 hp at 3400 rpm (Specifications)
- Rated torque : 44 mkg at 2200 rpm (Specifications)
- Gearing : 5-speed manual transmission; Availibility : from 02.1939 (Specifications)
- Gear ratios : I. 3.90; II. 2.88; III. 1.45; IV. 1.0 (Specifications)
- Final drive ratio : 3.08 or 3.60 (Specifications)
- Driven wheels : rear wheels (Specifications)
- Frame design : box-section pressed-steel low-bed frame (Specifications)
- Front-wheel suspension : double wishbone; Front springs : coil springs (Specifications)
- Rear-wheel suspension : swing axle, up to 1938 with additional compensating springs (Specifications)
- Brake system (foot brake) : hydraulic, with Bosch-Dewandre vacuum booster (Specifications)
- Steering : worm-and-nut steering (Specifications)
- Wheelbase : 3290 mm (Specifications)
- Maximum speed : 170 km/h (Specifications)
- Fuel tank: position / capacity : in the rear / 110 l (Specifications)
- Fuel consumption : 29 l (Specifications)
Accessed 2026-11-12
4
1939 Mercedes-Benz 540 K Special Roadster by Sindelfingen, Arizona 2017 Level C RM Sotheby's
- supercharged overhead valve inline eight-cylinder engine
- 5,401 cc
- synchromesh on third and a dog clutch on fourth
Accessed 2026-11-12

Research coverage

Production figures2 recorded

Technical data28 verified values

Factory coloursNot yet researched

Option codesNot yet researched

Chassis documented0 of 25

Photographs1

Shows what this archive has recorded so far – not how much of the history is known.

Editorial status

Reviewed · 2026-11-11

Revision history (4)

2026-11-11 Basic profile published from discovery research; production figure re-checked against its source page.
2026-11-12 Research gaps filled from sources (6 values).
2026-11-12 Research gaps filled from sources (27 values).
2026-11-12 Research gaps filled from sources (1 values).

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Mercedes-Benz
540 K Spezial-Roadster (Sindelfingen)

At a glance

Why it matters

How rare is it?

Production

History

Variants