The development of the 1955 Mercedes-Benz 190SL came about as a way to give everyday consumers a version of the powerful Mercedes-Benz 300SL. Unfortunately, in the opinion of many connoisseurs, it is not as well-regarded as its handsome and athletic older brother, and is not regarded as a real collectible.
The general consensus is that the 190SL is underpowered and lacks performance. If it is compared with its stable-mate, the 300SL, or the 507, then the criticism is valid. The 356 had less power, but it was much lighter and far more nimble.
Perhaps the fault lies with Mercedes-Benz itself and its approach at the time of the little 190SL's introduction. In its styling and general concept, it was regarded as a sports car by the press and the public alike, but the company quietly promoted it as a sports tourer. There was not a lot of conviction in the tourer stance though, and at the car's introduction, the manufacturer talked quite openly of a version specifically for the race track.
After the destruction of its Stuttgart factories during World War II, Daimler-Benz began its postwar reconstruction with limited production of the Mercedes Type 170 series sedan, complete with styling and a side-valve 1.7-liter four-cylinder engine that were strictly prewar. At the same time, postwar Germany desperately needed trucks and Daimler-Benz obliged.
The profits from these operations were plowed back into building new facilities, and in designing and developing important new models. While the prewar 170 was upgraded between 1946 and 1951, running in parallel was the development of a completely new range of luxury six-cylinder sedans and coupes. These appeared in 1951 as the 220 and 300, the engines of both models featuring a single chain-driven overhead camshaft.
With a successful prewar history on the racetracks of Europe with the all-conquering Silver Arrows, many Daimler-Benz engineers, particularly Rudolf Uhlenhaut, pushed for the company to re-enter motorsports. Formula 1 was out of the question -- the resources simply weren't available -- but developing a sports racing car using as many production components as possible from the new 300 series appealed to management.
Out of these discussions came the brilliant, but complex, 300SL. It was immediately successful, taking a fine second place to Ferrari in the 1952 Mille Miglia, victory in Bern, Switzerland, two weeks later, followed by outright victory at the grueling 24 hours at Le Mans.
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Introduction of the 1955 Mercedes-Benz 190SL
The introduction of the 1955 Mercedes-Benz 190SL was held in tandem with the debut of the more powerful 300SL, which overshadowed the 190SL almost from the beginning. The four-cylinder, two-seat sports car had a lot of solid qualities all its own, but just couldn't compete with its bigger sibling.
Mercedes-Benz's United States importer, Max Hoffman, an expatriate Austrian who became known as the "Baron of Park Avenue," wanted a production version of the 300SL to sell to his wealthy American clientele. But at the same time, he recognized the need for a less complex and more affordable sports car carrying the three-pointed star.
His vision was of a sports car utilizing major components from the sedan range but wrapped in a svelte, stylish body. Hoffman would be successful with both requests, the 190SL and 300SL having their world premieres at the New York Motor Show on February 6, 1954.
Although the development and engineering for the 300SL came from Uhlenhaut's racing department, the 190SL was developed by technical director Fritz Nallinger's passenger car team. Nonetheless, both shared very similar styling cues, in particular the smooth roundness of their respective designs and the new grille.
The tall, imperious radiator topped with a three-pointed star was forsaken on the SLs for a far simpler, open design; a wide rectangular opening edged with chrome trim and a large star-in-a-circle within. The theme has been retained in various forms on the SL range ever since.
By late 1951, the "Ponton" styling of the new W180 series 220 sedans was settled and production plans were well under way. Designers and engineers next began preparations during 1952 for the smaller W120 series 180 that would share a great deal of hardware with its big brother.
An offshoot of the W120 program was W121, which would become the 190SL. Early concepts of the 190SL were drawn in late September 1953 after the board had met earlier the same month with Hoffman in Stuttgart-Untertürkheim.
The 190SL's styling was developed by a small team under the direction of Karl Wilfert, Mercedes's chief stylist. While Friedrich Geiger designed the 300SL body, it was Walter Hacker and his people, including a young Paul Bracq (later to gain international recognition at BMW and Peugeot), who were responsible for the shape of the small sportwagen.
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1955 Mercedes-Benz 190SL Design
The basic shape of the 1955 Mercedes-Benz 190SL design was arrived at almost immediately. It featured headlights mounted at the leading edge of the front fenders, small strakes over the front wheel arch, a graceful curve up and over the rear fender to a sloping rear trunk, and, of course, the "open mouth" front air intake with the floating three-pointed star within.
The 190SL sat on a 94.5-inch wheelbase, coincidentally the same as the 300SL, but was much leaner in its lines. Wheel tracks were 56.3 and 58.3 inches front and rear, respectively, and overall length was 166 inches. Body width was a wide 68.5 inches.
It was a prototype 190SL that was displayed at the 1954 New York Motor Show to gauge buyer interest. The reaction was positive and development, particularly of the body style, continued.
For its second premiere at the Geneva Salon in March 1955, many styling touches from the prototype were modified in preparation for series production. Detail changes included:
- A redesigned hood with a smooth, full-length bulge replacing an ugly air scoop. Furthermore, the hood opening was shortened and hinged at the front.
- The grille shape was more rounded.
- Front fender profiles were altered slightly to raise their line into the doors.
- Strakes were added over the rear wheel arches, matching those at the front (Mercedes publications referred to these styling elements as "splash shields").
- Round front parking lights replaced rectangular units.
- The fuel filler was shifted from the lower right rear corner under a flap to a normal locked cap protruding from the rear panel to the right of the license plate.
- Mercedes-Benz scripts were removed from low down on the front fenders.
Inside, the dash was altered, too. The prototype's instrument binnacle was flat, shallow, and wide, with the minor gauges positioned between the speedometer and tachometer. For production, the binnacle projected slightly, was much taller and narrower, and the ancillary gauges relocated in a line below the two major dials.
The dash top was extensively padded to reduce sun glare and increase occupant safety. (An early press photograph even showed the 190SL with a column gearshift lever.) A neat touch, and perhaps an indication of how Mercedes-Benz marketing folks really saw the 190SL, was the provision of two sets of heater controls -- one for the driver and another for the passenger. This required two heater matrixes under the hood and two sets of air trunks.
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1955 Mercedes-Benz 190SL
Mechanically, the 1955 Mercedes-Benz 190SL was very advanced for the year of its introduction on the world market. Like the W180- and W186-series six-cylinder sedans, the 190SL's four-cylinder engine would feature a single, chain-driven overhead camshaft operating staggered valves via pivoted long-and-short rocker arms. Designated M121, it shared nothing with its sedan counterpart's aged side-valve engine.
The M121 engine was the first of a new four-cylinder engine family developed by the team led by Hans Scherenberg. Karl-Heinz Goschel is generally recognized as the key engineer in the development program.
Although the M121's cylinder-block material was cast iron and not aluminum alloy, as in the 300SL, the two did have 85mm cylinder bores in common. The stroke of the four-cylinder's forged three-bearing crankshaft was 83.6mm, giving a capacity of 1897cc. (Why the 88mm stroke of the six's crank was not retained to give a full 2.0-liter capacity has never been revealed.)
On a compression of 8.5:1 and with two side-draft, twin-choke Solex 44 PHH carburetors, Mercedes initially claimed 110 horsepower (125 SAE) at 5,500 rpm and maximum torque of 114 pound-feet at 4,000 rpm. By the time the 190SL went into series production, advertised power was reduced slightly to 105 bhp at 5,700 rpm and torque to 105 pound-feet at 3,200 rpm.
Standing upright in the engine bay -- there wasn't room to lay it over as in the 300SL -- the under-hood view was highlighted by the cast aluminum plenum that channeled air from the circular air cleaner mounted on the bulkhead to the carbs. Tucked away under the carburetors was a four-into-one fabricated exhaust manifold; despite the overhead camshaft, the M121 engine's sophistication did not run to a cross-flow cylinder head.
The four-speed all-synchromesh gearbox was modified to accept a remote floor gearshift linkage. First prototypes were seen with a long, cranked lever that originated from well under the dash, but by production, this had given way to a neat central floor lever.
Suspension was, in the Mercedes-Benz tradition, independent all around. At the front were classic upper and lower wishbones with coil springs, while at the rear was D-B's famous single-pivot swing-axle. Coil springs were mounted on long trailing arms with rubber bushings to minimize noise transfer.
Mounted horizontally above the differential was another coil spring that Mercedes referred to as a "compensating" spring designed to reduce camber variations during wheel movement. This low pivot-point system evolved out of Mercedes's 300SL racing program. The same system would appear on the 220 series sedans and, later, on the 190 sedans.
Braking also had a competition heritage. All four wheels carried finned aluminum nine-inch drums with steel liners. The front drums had twin-leading shoes, with leading-and-trailing shoes at the rear. An ATE Hydrovac booster was an option when production began, but from mid-1956 onward, it was fitted as standard.
As on the new 220 sedans, the 190SL had a completely new self-supporting frame-floor system. It comprised a deep central tunnel, to accommodate the tail-shaft, flanked by rigid, welded box-section sills with a ribbed, pressed steel floor panel. The body panels were welded to this assembly.
Bolted to the front of this rigid frame was a demountable engine subframe. It attached at three points, all rubber insulated, and enabled the front suspension, steering, engine, and gearbox to be mounted as a unit on the assembly line, as well as facilitating simpler maintenance when the time came.
To learn how these features translated where it really counts -- on the road -- see the next page.
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1955-1963 Mercedes-Benz 190SL Road Tests
Over the course of its run, 1955-1963, Mercedes-Benz 190SL road tests were conducted by independent reviewers to assess its performance and handling.
The 190SL displayed at Geneva in March 1955 was one of a small series of preproduction cars leading to the official announcement and release in May. Offered in roadster form with the availability of an optional aluminum hardtop, it was received with some reserve by the press.
But it was beautifully built, in the Mercedes tradition, and solid in a way for which sports cars were not noted. Finish everywhere was near perfect in detail, whether under the hood, in doors that swung shut with almost no pressure and closed with that "clunk" that spelled solidity and strength, the millimeter-perfect body cut lines, or the immaculately upholstered interior and tailor-made set of suitcases.
Mercedes-Benz advertised the 190SL as a touring sports car, perhaps a car to compete in club hill climbs and rallies, but not the long-distance classic events. To support this view, Daimler-Benz even catalogued a production Sportausführung, a sports roadster that featured such lightening measures as cut-down aluminum doors minus the window winding mechanism and glass, and a small plexiglass aero screen for the driver. Mechanically, it was unchanged. How many were made is not recorded in the usually meticulous Daimler-Benz archives.
Road & Track, that most cosmopolitan of American motor magazines, tested the 190SL and made several positive comments. "Very few sports cars have been so eagerly awaited or so long in coming as the moderately priced SL version of the Mercedes-Benz...The net result is a car which is slightly more expensive and a little heavier than was originally planned, but certainly
it should be durable, dependable and without 'bugs.'"
Road & Track went on to say, "The outstanding achievement of the 190SL is without a doubt its quality in design and workmanship. But a close second is the general feeling of solidity which it immediately conveys." The magazine's test car ran a 0-60-mph time of 13.0 seconds, the standing quarter in 19.3, and a top-speed average of 99.8 mph, with a best run of 102.6 mph. Road & Track was impressed, even though the list price in New York was a tall $3,998.
Five years later, Road & Track again tested the 190SL and wrote, "To evaluate the Mercedes-Benz 190SL properly, one must first put the car into its proper category. First, this is not a sports car -- as far as we know no one has entered a 190SL in a sports car race for several years."
Testers remained impressed with the car's character and build integrity, commenting, "The steep price ($5,129) tag seems a little more plausible when one looks over the details and sees the quality of the car's interior." Apart from the enlarged rear window on the hardtop and the fitting of a clock on the glove box lid as standard, the car was unchanged.
This time, Road & Track managed a 0-60 run in 13.5 seconds (slightly slower), the quarter-mile in 18.9 seconds (slightly quicker), and a better maximum speed of 106 mph. "We say it's well worth the money," the publication concluded.
Across the pond in England, The Autocar tested the 190SL and ended its report by saying, "The 190SL was approached with keen expectation, knowing the reputation of its makers for quality and workmanship. It proved to be fast and tireless, exhilarating to drive, and was obviously created with long distance, comfortable travel in mind rather than competition work." Autocar testers produced a maximum speed of 106 mph, a 0-60 time of 13.3 seconds, and a 17.8-second quarter.
Sadly, many motoring journalists compared the performance of the 190SL with its 300SL sibling and found it wanting. The far more logical comparisons should have been with its homegrown rivals.
Across town in Stuttgart-Zuffenhausen, Porsche was producing its exquisite little 356 that, in 1600 form, produced 75 horsepower at 5,200 rpm, zipped from rest to 60 mph in 8.3 seconds, and matched the 190SL for maximum speed and build quality, but was lighter and less well equipped in keeping with its more overtly sporting character.
To the north, in a factory in Bremen, the Borgward Group was building the pretty Isabella TS coupe that was also available in limited numbers as a cabriolet. It was powered by a smaller 1493cc engine putting out 75 bhp, was superbly made, and its performance, too, matched the Mercedes. Its handling qualities were more in keeping with what a Mercedes buyer expected, whereas the Porsche 356 driver reveled in the tail-out oversteer from its rear-engine configuration.
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1950s Mercedes-Benz 190SL Development
There's no doubt that Fritz Nallinger and his team held no illusions about the 190SL's lack of performance, which led to 1950s Mercedes-Benz 190SL development. Even though many critical comments were ill-informed, they must have irked engineers like Hans Scherenberg and Karl-Heinz Goschel.
Nonetheless, the corporate parts bin contained sufficient goodies for some potentially exciting alternatives to be built and tested during the mid-1950s.
It was in the engine department where the 190SL was lacking most in their opinion. (The four-cylinder engine was jokingly referred to by the engineers as the Rappelkönig, or "rattle king.") In January 1954, Scherenberg and Goschel were asked to look at new developments.
Goschel, the fuel injection specialist responsible for the 300SL's system, decided to apply some of the technology from the M198 engine to the 190SL. A new engine designation -- M126 -- was given to this research. A completely new cylinder head casting was produced with crossflow porting. High-pressure Bosch mechanical fuel injection and desmodromic valve gear were adapted from the M198 powerplant.
In October 1955, the test department completed assembly of a prototype 190SL/1 equipped with the M126 engine that produced 117bhp at between 5,900 and 6,100 rpm on the test stand.
A further three cars (190SL/6, -8, and -9) were commissioned and tested, car nine eventually covering some 41,500 kilometers (more than 25,750 miles). However, the engine proved to be no more sophisticated than the production M121 unit, was only marginally more powerful, and would have been far more expensive to produce.
Rudolf Uhlenhaut, a man who loved fast and powerful cars -- he had a very special 300SLR built for his private use -- had some ideas on improving the 190SL. His solution was simple: Power the 190SL with a 3.0-liter six-cylinder engine from the 300 series.
The task of modifying the 190SL was given to Kurt Oblander, a recent recruit to Mercedes-Benz. The W121 engine bay was not designed for an engine as physically large as the 300's six, so Oblander built a parts-bin engine. To the 300SL block that he canted at 50 degrees, he took an M198 cylinder head and fitted it with three Solex 32 PAIAT carburetors (the injection system was too bulky), added an air filter from the 300Sc, and fabricated a new intake manifold, sump pan, water pump, and exhaust system.
Initial power output was 139 bhp, but this was quickly raised to 151 horsepower at 5,100 rpm. The engine was squeezed into prototype 190SL/3 and entered in the 1956 Alpine Rally. Its power and acceleration were far superior to that of the standard 190SL, although weight distribution was inferior, but again the costs of production were prohibitive. Another blind alley.
By far, the most exciting avenue of development was that christened W127, in which the engineers fitted the M180 2.2-liter six-cylinder engine that was a prototype from Goschel's fuel injection test program. Using a touring specification camshaft, it produced an easy 117 bhp and had better torque characteristics than the carbureted version of the same engine.
Body modifications were necessary to fit the longer six in the 190SL's engine bay. The prototype department remodeled the engine bulkhead with a special six-inch recess.
The strength of the transmission tunnel was increased by using one from the W104 that had thicker metal and added gussets around the rear of the passenger compartment.
The six-cylinder engine and a four-speed gearbox were assembled onto the production subframe, which was in turn bolted up to the W121 bodyshell as usual. The first prototype used by Erich Waxenberger in this program was car 190SL/4, followed soon after by 190SL/5.
While he reported that weight distribution was not as good as in the normal 190SL, the driving characteristics were good with the exception of the front springs being too soft. In June 1956, the two W127s had their baptism of fire on the Nordeschleife circuit of the Nürburgring with Rudi Uhlenhaut and Karl Kling as drivers.
They lapped in perfect concert with each other in a time of 11 minutes, 29 seconds for lap after lap. Arthur Mischke, in a regular 190SL, was only able to manage lap times that were a good 25 seconds slower. Further tests continued on the Gross Glockner and other alpine areas.
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Motivated by these test results, Nallinger proposed that the Mercedes-Benz W127 be placed in the Mercedes-Benz program, with production commencing on July 1, 1957.
In his report, Nallinger said of the 190SL with the M180 fuel-injected engine (in effect the W127): "This car performs beautifully with all vibrations and resonance inside gone. The vehicle has a cultivated appearance, strong acceleration, and drives very comfortably. It will surely be favored by our customers.
"The body stiffness is slightly reduced but we will soon find a constructive solution for the installation." From September 1956, Nallinger had penned the 220SL, as it had by now been referred to internally, into the range. He had even planned to show it at the Frankfurt auto show in 1957. At the time there were discussions about producing the 220SL only, or perhaps offering the 220SL as an in-between model between the modestly powered 190SL and the high-powered 300SL.
At the board meeting of April 12, 1957, it was concluded to build both the 190SL and the 220SL. However, a production problem reared its head. Hans Moll, works chief at Untertürkheim, advised Nallinger that the new tooling for production of fuel-injected six-cylinder engines would not be ready for their release timetable.
Meanwhile, testing continued. Goschel achieved 130 bhp with the touring camshaft, while Waxenberger racked up the test miles in cars four and five. His only negative comment concerned the car's tendency to over-steer when cornering at high speed. He noted wryly that by carrying an 80kg (176-pound) weight in the trunk, the car became far more balanced and handled in a similar manner to the 300SL roadster!
In view of the difficulties, the W127 program was continued, but with reduced urgency because sales of the 190SL were still strong worldwide. Concurrent with these activities, Nallinger was also overseeing the design and development of the new S-class cars (Will and W112) that would introduce new body manufacturing technology.
At board level, he questioned whether production difficulties might arise with the mixing of the new monocoque Will body and old W127; he believed that there was a contradiction with the old on the one side and the totally new aggregates on the other.
As production of the W127 could not begin before 1960, Nallinger instead proposed to develop a completely new 220SL using the technology developed for the Will. This led to the development of the W113 that became known as the 230SL and featured designer Bela Barenyi's famous "pagoda" roof.
The W127 became important, after all, in the story of the SL cars from Mercedes-Benz because it was the link between the past, represented by the 190SL, and the future, the 230SL.
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1955-1963 Mercedes-Benz 190SL
The first Austin Healey, the 100, had a 2.6-liter four-cylinder engine with a similar power output of 102 bhp at 4,000 rpm, but was quicker, accelerating from 0-60 mph in 8.5 seconds, and had a similar maximum speed of 106 mph. (The later 100 Six, with its six-cylinder engine that also displaced 2.6 liters, was actually slightly slower.)
The Triumph TR3 acclerated faster -- 7.5 seconds to 60 mph -- but its top speed was much the same at 105. The MGA was quite away off the pace with just 78 horsepower at 5,500 rpm, a 96-mph top speed, and at least 9.1 seconds for the 0-60 sprint.
Only the awkwardly styled Daimler SP250 had the legs on its peers, the marvelous 2.5-liter "hemi" V-8 pumping out 140 bhp at 5,800 rpm and pushing it to a maximum of 123 mph while taking just 6.8 seconds for the 0-60-mph run.
Underpowered and overweight (at around 2,500 pounds), the 190SL was never really designed for the harsh glare of international competition. It did compete successfully in the 1957 Nassau Speed Week, and competed with varying degrees of success in races and rallies in Macau and Hong Kong, as well as the occasional outing in restricted events in Europe. In 1961, a 190SL fitted with a diesel engine set some speed and distance records on the Hockenheimring.
Even though respectable numbers of the 190SL were built and sold around the world, there is a lack of quality information available about it. It gains scant mention in Beverley Rae Kimes's tome The Star and The Laurel published by Mercedes-Benz of North America to celebrate the centennial of Daimler-Benz; Richard Langworth's book Mercedes-Benz: The First 100 Years has but a few pages devoted to it.
The "little brother" of the 300SL has had to live in the shadow of its more illustrious sibling. That has been a burden it has borne rather well judging by the number of well-kept and appreciated 190SLs that have survived. It is true they don't command the mega-buck prices of the 300SL, but that merely makes them more available and more used.
Beginning with the release of the sensational new finned 220S and SE sedans in 1959, both the 300SL (now a roadster in place of the "gullwing" coupe) and 190SL found themselves nearing the end of their useful careers. In 1963, the company displayed its new "Pagoda"-roofed 230SL that set an entirely new direction for Mercedes-Benz automobiles bearing the famous SL badge.
Richard Langworth summed it up rather well when he wrote, "Had it been built by anybody else, the 190SL would be regarded today as a classic in its own right."
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