230 SL (1963–1967)
Production of the 230 SL commenced in June 1963 and ended on 5 January 1967. Its chassis was based on the W 111 sedan platform, with a reduced wheelbase by 30 cm, recirculating ball steering (with optional power steering), double wishbone front suspension and an independent single-joint, low-pivot swing rear-axle with transverse compensator spring. The dual-circuit brake system had front disc brakes and power-assisted rear drum brakes.[6] The 230 SL was offered with a 4-speed manual transmission, or an optional, very responsive fluid coupled (no torque converter) 4-speed Mercedes-Benz automatic transmission, which was popular for US models. From May 1966, the ZF S5-20 5-speed manual transmission was available as an additional option, which was particularly popular in Italy. Of the 19,831 230 SLs produced, less than a quarter were sold in the US.
The 2308 cc M127.II inline-six engine with 150 PS and 196 Nm torque was based on Mercedes-Benz' venerable M180 inline-six with four main bearings and mechanical Bosch multi-port fuel injection. Mercedes-Benz made a number of modifications to boost its power, including increasing displacement from 2197 cc, and using a completely new cylinder head with a higher compression ratio (9.3 vs. 8.7), enlarged valves and a modified camshaft. A fuel injection pump with six plungers instead of two was fitted, which allowed placing the nozzles in the cylinder head and "shooting" the fuel through the intake manifold and open valves directly into the combustion chambers.[7] An optional oil-water heat exchanger was also available.
Mercedes-Benz Chief Engineer Rudolf Uhlenhaut demonstrated the capabilities of the 230 SL on the tight three-quarter mile Annemasse Vétraz-Monthoux race track in 1963, where he put up a best lap time of 47.5 seconds vs. 47.3 seconds by Grand Prix driver Mike Parkes on his 3-liter V12 Ferrari 250 GT.[8]
A brief chronology of the most notable changes made to the 230 SL:[9]
- 10/1963: First 230 SL with automatic transmission.
- 09/1964: Spare tire well removed, tire mounted horizontally.
- 11/1964: Optional tinted/thermal glass and new soft-top with steel bows (distinguished by missing chrome trim on the outer trailing edge).[10]
- 04/1964: US models with radio Becker Europa TR instead of Europa TG.
- 08/1965: Some harmonization with new W 108/W 109 sedans, incl. new floor panels, combined brake and clutch fluid reservoir, boot light and interior changes. US models with hazard lights.
- 03/1966: Mounts for three-point seat belts added.
- 05/1966: Optional ZF 5-speed manual transmission; rare and now very desirable.
250 SL (1966–1968)
The 250 SL was introduced at the 1967 Geneva Motor Show. Production had already commenced in December 1966 and ended in January 1968. The short one-year production run makes the 250 SL the rarest of the W 113 series cars. The 250 SL retained the stiffer suspension and sportier feel of the early SLs, but provided improved agility with a new engine and rear disc brakes. Range also improved with increased fuel tank capacity from 65 L to 82 L. Like its predecessor, the 250 SL was offered with a 4-speed automatic transmission, and 4-speed or ZF 5-speed manual transmissions.[11] For the first time, an optional limited slip differential was also available. Of the 5,196 250 SLs produced, more than a third were sold in the US.
The main change was the use of the 2496 cc M129.II engine with 6 mm increased stroke, 2 mm increased valve ports, and seven main bearings instead of four. The nominal maximum power remained unchanged at 150 PS, but torque improved from 145 lbft to 159 lbft.[11] Resiliency also improved with a new cooling water tank ("round top") with increased capacity from 10.8 L to 12.9 L, and a standard oil-water heat exchanger.
The wider power band of the 250 SL resulted in noticeably improved performance, as the 230 SL engines rarely produced more than 143 PS in practice.[8]
California Coupé
The 250 SL also marked the introduction of a 2+2 body style in 1967, the so-called "California Coupé", which had only the removable hardtop and no soft-top: a small fold-down rear bench seat replaced the soft-top well between passenger compartment and boot. A 280 SL California version was introduced in 1968.
Midlife improvements
In August 1967, a number of additional changes were incorporated to accommodate stricter safety regulations and US emission laws. The safety improvements included a collapsible steering wheel and padded wheel hub, concave control knobs, elastic black rubber heater levers (instead of rigid coloured translucent plastic), and softer, rounded dash top padding. Door handles, locks, and window cranks were modernized and less protruding, the door pockets were elastic, the rear-view mirror frame was black plastic instead of chrome, and the side view mirrors became more angular. Essentially, the 1967 250 SL retained the more classic "chrome" interior of the 230 SL, whereas the 1968 250 SL introduced the modernized "safety" interior of the 280 SL.
US models acquired side reflectors on the fenders, Kangol three-point seat belts, an illuminated automatic gearbox shift quadrant, and emission control equipment. The chrome horn ring was changed to matte finish.
280 SL (1967–1971)
The 280 SL was introduced in December 1967 and continued in production through 23 February 1971, when the W 113 was replaced by the entirely new and substantially heavier R107 350 SL. Over the years, the W 113 evolved from a sports car into a comfortable grand tourer, and US models were by then usually equipped with the 4-speed automatic transmission and air conditioning. Manual transmission models came with the standard 4-speed or the optional ZF 5-speed, which was ordered only 882 times and thus is a highly sought-after original option today. In Europe, manual transmissions without air conditioning were still the predominant choice. Of the 23,885 280 SLs produced, more than half were sold in the US.
The main change was an upgrade to the 2778 cc M130 engine with 170 PS maximum power and 180 lbft maximum torque, which finally gave the W 113 adequate power. The performance improvement was achieved by increasing bore by 4.5 mm, which stretched the limits of the M180 block. This required ungrouping the existing pairwise cylinder casts to improve thermals with cooling water passages between all cylinders, and mandated an oil-cooler, which was fitted vertically next to the radiator. Each engine was now bench-tested for two hours prior to being fitted, so their power specification was guaranteed at last.[10]
The M130 marked the final evolution of Mercedes-Benz' venerable SOHC M180 inline-six, before it was superseded by the new DOHC M110 inline-six introduced with R107 1974 European 280 SL models. For some time, it was also used in the W 109 300 S-Class
North American models
North American models have a number of subtle differences, the most obvious one being the distinctive "sealed beam" bulb headlights required in the US versus the Bosch Lichteinheit headlights for the rest of the world.[12] 1970 US models also acquired amber turn-signal lenses on the rear lights, later than most other countries.[13]
Other differences of the North American models include imperial gauges, chrome bumper guards, side reflectors (illuminated from 1970), lower rear-axle ratios for faster acceleration yet reduced top speeds, and no "single-side" parking lights. US market 280 SL engines required emission control modifications, including "softer" valve timings, a reduced compression ratio and a modified injection pump, which reduced power from 170 PS to 160 PS.[8] In the US, automatic transmission, air conditioning, and white wall tires were much more popular than elsewhere.
European cars were popular US gray-market imports: those vehicles were brought to the US some years after their original delivery in Europe. Early European imports had aftermarket hazard lights and Kangol seat belts fitted, US safety requirements that were adopted in Europe only in later production years.
Special versions
Pininfarina Coupé
While the original design by Paul Bracq is regarded highly today, it was more controversial at the time of its introduction. So in 1963, Pininfarina asked the Mercedes-Benz board to create its own custom-bodied version of the 230 SL. Pininfarina's Tom Tjaarda turned the roadster into a fixed-head coupé that vaguely resembled the Ferrari 250 GT Lusso.[8] He retained the grille and headlamps of the original, but raked the grille more sharply, sculpted the wings, and made the sides more bulbous and thus wider, while making the bonnet narrower and shorter. The rear was reminiscent of the Ferrari 330 GT 2+2 (also a Tjaarda design), but without taking away the distinctive personality of the 230 SL.[16] Inside, Tjaarda left the dashboard unchanged, but the interior as a whole exuded the stamp of elegant Italian hand craftsmanship known from contemporary Ferraris.[8]
Pininfarina Coupé
While the original design by Paul Bracq is regarded highly today, it was more controversial at the time of its introduction. So in 1963, Pininfarina asked the Mercedes-Benz board to create its own custom-bodied version of the 230 SL. Pininfarina's Tom Tjaarda turned the roadster into a fixed-head coupé that vaguely resembled the Ferrari 250 GT Lusso.[8] He retained the grille and headlamps of the original, but raked the grille more sharply, sculpted the wings, and made the sides more bulbous and thus wider, while making the bonnet narrower and shorter. The rear was reminiscent of the Ferrari 330 GT 2+2 (also a Tjaarda design), but without taking away the distinctive personality of the 230 SL.[16] Inside, Tjaarda left the dashboard unchanged, but the interior as a whole exuded the stamp of elegant Italian hand craftsmanship known from contemporary Ferraris.[8] The car never went into production and remained a one-off that was subsequently acquired by German press baron Axel Springer. In 2022, it sold for $1.2m from a private collection in California.[17]
W 113/12
Mercedes-Benz Chief Engineer Rudolf Uhlenhaut liked pushing the power envelope of his cars. In 1965, he fitted a 250 SL with the massive 6332 cc 250 PS M100 V8 engine from the Mercedes-Benz 600. This engine conversion gave the car, denoted as W 113/12, impressive power, but made it very front-heavy, so that this direction was abandoned. The car was eventually destroyed, the usual procedure for test vehicles at the time.[9]
Frua Shooting Brake
In 1966, the Turin coachbuilder Pietro Frua, a prominent car designer in Italy in the 1960s, presented a coachbuilt 230 SLX Shooting Brake version of the 230 SL.[18]
R 113 W 33-29
In 1968, Mercedes-Benz fitted a 280 SL with a 206 PS M50F Wankel engine, denoted as R 113 W 33-29. With a top-speed of 205.1 km/h, a 0-60 mph (97 km/h) acceleration time of 8.7 seconds, and almost inaudible compared to regular SLs, it provided quite a surprise encounter for their owners in southern Germany at the time.[9]
