Mercedes-Benz SL-Class History

29 Jan 2015 | Author: | Comments Off on Mercedes-Benz SL-Class History
Mercedes SL 350

Used Models

Automotive icons don’t come more substantial than the Mercedes-Benz series of SL luxury roadsters. But the first SL wasn’t a roadster and, despite that, it’s still considered the greatest example of the breed. The SL story is really about the evolution of two ideas: The first produced a legendary coupe for both the street and track.

The second has sired generations of elegant, capable and lavishly engineered open two-seaters.

Each generation of the SL has been exceptionally long-lived. Over more than half a century, there have only been five full-size SLs and two smaller near SLs (the 190SL of the late ’50s and early ’60s and the current SLK). That means an average SL stays in production for a full decade.

The Original 300SL Coupe (1954-1957)

Daimler-Benz recovered rapidly from the devastation of World War II and was producing Mercedes cars again by 1946 #151; albeit a virtually unchanged version of the 1942 model 170 sedan. Before the war, the company had considered racing (and winning) a critical part of both its engineering development and public image, and there was no reason for that to change after the war.

By the early ’50s, Mercedes was ready to reenter motorsports. It looked at immediately going into Grand Prix racing, but on June 15, 1951, the Board of Management ultimately decided its initial efforts should be aimed at winning the 24 Hours of Le Mans. Less than a year later, in March 1952, the company showed the prototype for the sports car built to do that, the 300SL Coupe.

This first 300SL was built around a tubular space frame chassis and was powered by a version of the 3.0-liter, SOHC straight six that had been developed for the then-new 300S sedan, formal coupe and convertible. In the 300SL, everything was optimized for performance.

The 175-horsepower high-compression engine was tilted 45 degrees toward the passenger side to lower the cowl and hood, the suspension was independent both front and rear (though the rear used rather diabolical swing axles), and the aerodynamically efficient skin was made of aluminum. However, because the space frame’s design depended on interlacing small tubing running high along the car’s sides for strength, conventional doors were impossible on the 300SL racecar.

Faced with that quandary, Mercedes engineers set about finding a new way for drivers to enter and exit their developing sports car. What they came up with were doors cut deep into the roof and hinged at their top, so that they swung up to open. And when open, they resembled the wings of a seagull.

Naturally, the doors quickly picked up the popular nickname gullwing doors and soon after that, so did the car itself.

On that first racing prototype, the doors didn’t extend down much beyond the side windows so getting in or out took real gymnastic ability. Plus, no one ever really explained how they’d get out of a 300SL should it wind up on its roof after a crash. But no matter, the car was a sensation.

It was the first truly modern post-war sports car whose sleek lines had a negligible coefficient of drag; the suspension was advanced, and there was just 1,930 pounds spread over its 94.5-inch wheelbase and 166-inch overall length.

In May, the 300SL made its competition debut at the 1952 Mille Miglia, the epic 1,000-mile open road race that ran the length of Italy. Three 300SLs entered the race, but the winner was a Ferrari 250S. It would be one of the few times the 300SL didn’t win that year. In June, 300SLs came home both first and second at Le Mans accomplishing the goal set out for the car. Then they won at the Nurburgring, and again at Mexico’s Carrera Panamericana road race.

The 300SL Coupe race machine was all that it was supposed to be and more. So there was nothing left for it to do, and after 1952, Mercedes abandoned sports car racing to concentrate on Grand Prix events with the astounding single-seat, eight-cylinder W196.

With its racing legend secured, the 300SL could have faded away. But Mercedes’ U.S. importer, Max Hoffman, thought there would be a market in North America for a road-going version of the car. On the strength of Hoffman’s passion, and his order for 1,000 300SLs, Mercedes began developing the production machine.

And at the 1954 New York Auto Show, the production version of the 300SL was shown for the first time.

Sharing its distinctive profile and signature door design with the racecar, it was impossible to mistake the road-going coupe for anything but a 300SL. But in fact the road car was much more civilized and, in many ways, more ambitious than the racer.

With its slab sides and austere decoration the racecar wasn’t suitably ornate for a 1950s road machine #151; even for a Mercedes. So the body was redesigned with cooling vents, chrome trim, a bold three-pointed star in its grille, eyebrow protrusions over each wheel well and larger, deeper cut gullwing doors that allowed easier ingress and egress and also had small wing windows for at least some ventilation. Also instead of being built of aluminum, most of the road 300SL’s body was steel with an aluminum hood, doors and trunk lid (29 all-aluminum road-going 300SLs would be built after 1956).

Carrying over more or less intact from the racecar were the tubular space frame, the independent suspension and the huge ventilated drum brakes. But while the engine was still based on the 3.0-liter, SOHC straight six from the 300S sedan (and still sat at a 45-degree angle under the hood), it now sported a groundbreaking gasoline direct injection system.

The injectors were mounted in the upper part of the cylinder wall where the spark plugs would be in a standard 300 engine, and the spark plugs were in turn moved to the side of the cylinder head. Add in a high (for the time) 8.55-to-1 compression ratio and a dizzying (for the time) 6,600-rpm redline and the result was a thrilling 215 horsepower at 5,800 rpm. Keeping in mind that the same engine (with less compression, a milder cam and carburetors) was making just 115 horsepower in Mercedes’ 300 sedans, and the accomplishment of the SL’s engine becomes obvious.

Luxury equipment like sound-deadening leather upholstery and fitted luggage bounced the ’54 300SL’s weight up past 2,700 pounds and its price to a lofty $11,000 #151; nearly twice what GM was asking for its most expensive car that year, the $5,875 Cadillac Eldorado.

The 300SL was one of the best sports cars of its era. Stirring the all-synchromesh four-speed gearbox, Britain’s Motor Sport magazine had the 300SL coupe zipping to 70 mph in just 8.5 seconds and attaining a studly 146-mph top speed. The effect is electrifying, wrote Autocar about the car’s acceleration.

Motor Trend ‘s test had the 300SL hitting 60 mph in 8.5 seconds and the quarter-mile flashing by in 16.1 ticks of the clock. Quick though the 300SL was, it would be a mistake to call it easy or forgiving. With its swingarm rear suspension, the change in rear tire camber could be quite extreme, leading to a sudden onset of oversteer.

But in the hands of an expert, that trait could be managed.

As production of the 300SL ramped up, Mercedes was able to cut the price so that in 1955 it could be had for less than $7,500. But even at that low price, the coupe’s appeal was limited by its rather tough-to-overcome tall and wide door sills, limited luggage space and notoriously toasty interior (air conditioning was not an option). If the SL were to go forward, Mercedes knew it would have to produce one tamed for the gentlemen with means who shopped Mercedes. So after building 1,400 Gullwings, Mercedes replaced the coupe with a new, more civilized open roadster for the 1958 model year (production actually began in the summer of 1957 ).

By the way, SL originally stood for Sporty and Light. The original coupe will always be the sportiest SL and the last one that could accurately be described as light.

The 300SL Roadster (1958-1963)

Though destined to always be overshadowed by its charismatic Gullwing brother, the 1958 300SL roadster was in many ways the first true SL as we know it today. Built atop the same basic frame, using the same basic drivetrain and having a body similar to the coupe, the roadster nonetheless projected its own aura of dignity, elegance and power.

To build the roadster, Mercedes strengthened the center tunnel portion of the chassis and the sides were revised to allow the fitment of conventional doors. The rear suspension was tamed somewhat by moving the pivot points for the swing axles lower in the chassis and by adding a supplementary spring mounted transversely above the differential and linked to the axles via vertical struts. Also improving the handling were wider front and rear tracks and wider tires.

The roadster also benefited from engine refinements, including a new camshaft and a higher (9.5 to 1) compression ratio, that bumped output to 235 horsepower. But it also weighed over 200 pounds more than the coupe, which meant performance was virtually identical.

From the outside, the most readily apparent differences between the coupe and roadster (besides the obvious decapitation) were the adoption of a wraparound-style windshield and new bezels that grouped the headlights, side marker lights and turn signals into a single, very attractive unit. Less obvious was the incorporation of a real, usable trunk. In 1961 . the 300SL also got four-wheel Dunlop disc brakes for the first time.

It was a far more civilized car than the Gullwing, but sales were less than spectacular. With prices in 1958 once again hovering at nearly $11,000, that’s hardly surprising.

Offered with both a soft retracting roof and a bolt-on hardtop, the 300SL set the standard by which all future SL roadsters would be judged. But even though Mercedes built more roadsters (a total of 1,858) than Gullwing coupes, they would never match the former car’s iconic status.

The 190SL (1955-1963)

Except for the SL part of its name, some styling cues and the fact that it was a two-seat roadster, the 190SL was unrelated to the 300SL roadster. Based on the mechanical components of the prosaic 180-Series sedan, the four-cylinder-powered 190SL was always perceived as underpowered and not particularly sporty in its handling. But it was pretty.

An early prototype of the 190SL actually appeared alongside the 300SL Gullwing coupe at the 1954 New York Auto Show. With its open grille filled with a big Mercedes star and pontoon fenders featuring eyebrows over the wheel openings, the 1955 190SL had a family resemblance to the 300SL. But with its drooping rear and fender-capping taillights, it also looked an awful lot like a 1950 Studebaker Commander, particularly when fitted with the optional bolt-on hardtop.

Since the Commander had been drawn by the famed Raymond Loewy and is generally considered a design classic, the resemblance was not necessarily a bad thing.

Under that skin (the doors, hood and deck lid of which were aluminum) lay the 180-Series suspension and structure; a simple amalgamation of stamped steel panels, double wishbones up front and the low pivot point, often ornery, swing axles in the rear. However, the 180-Series engine, a 1.8-liter L-head iron-lump four, was rated at just 52 feeble horsepower in the sedan.

So instead the 190SL got a new 1.9-liter, OHC four breathing through twin Solex carburetors to make 120 horsepower when it entered production early in 1955. The engine sat upright in the nose and the only transmission was a floor-shifted four-speed manual. Eventually, the 1.9-liter engine would find its way into the sedans to produce the 190-Series and would grow in displacement to power Mercedes’ mainstream midsize models through the ’60s and into the ’70s.

Compared to such contemporaries as the 95-horsepower Triumph TR3 or 72-horsepower MG MGA, the 190SL wasn’t at all underpowered, but it was significantly heavier than those traditional sports cars. Perhaps if it hadn’t shared showrooms and the spotlight with its bigger brother, it would have been considered among the best sports cars of the era. But it wasn’t a Triumph or an MG, it was a Mercedes, and many sports cars shoppers dismissed it as a half-hearted car.

The 190SL stayed in production through the 1963 model year virtually unchanged and, despite critical indifference, was quite popular. The 25,881 190SLs sold probably emboldened Mercedes more than the legendary Gullwing in its decision to go forward with the SL.

The Pagoda Roof W113 SL (1963-1971)

The original 300SL established the SL name, but it was the family of SLs, starting with the 1963 230SL, that made it big business for Mercedes. Effectively replacing the 190SL and 300SL, the ’63 230SL was about the same length as the 190SL, but about the same width as the 300SL and, like the 300SL, powered by a fuel-injected six-cylinder engine. It was plusher than the 190SL, but less expensive than the lavishly detailed 300SL, and so civilized that it was the first SL to be offered with air conditioning and an automatic transmission.

With its square cut lines, the 230SL set the styling idiom for subsequent Mercedes products throughout the ’60s. But it was the optional hardtop, which dipped at the center, that was the car’s most distinctive feature. It was designed to maximize the height of the side windows to improve visibility and ease getting in and out of the car.

The result was a roof that looked like a pagoda, and that became the name that stuck with the car.

Like the 190SL, the 230SL’s chassis was strictly conventional (for a Mercedes). The suspension consisted of double wishbones up front and the rear still had those somewhat nasty swing arms. The body was mostly made of steel, except for the doors, hood and deck lid, which were aluminum. Mercedes also claimed that this new SL was the first sports car to feature a rigid cockpit protected by front and rear crumple zones (which the company had pioneered on its sedans).

It was the first passenger car to have an alternator rather than a generator and the first sports car with an automatic transmission (conveniently overlooking that the first Corvette in 1953 was offered only with a two-speed automatic).

Power for the 230SL came from a slightly enlarged version of the 2.2-liter OHC straight six then powering the maker’s mid- and full-size sedans. Displacing 2.3 liters and breathing through Bosch mechanical fuel injection, it was rated at a full 170 horsepower. The manual transmission was a conventional four-speed, but the optional automatic used a fluid coupling instead of a torque converter and functioned as a clutchless semiautomatic.

The 230SL was a sensation, attracting not just men but #151; thanks to the automatic transmission, elegant appearance and tasteful appointments #151; women. It wasn’t really a sports car as much as a relentlessly practical (even the trunk was large) two-seater of grace, luxury and competence. And Mercedes didn’t tamper with it much over the next eight years.

In 1967 the SL’s engine grew to 2.5 liters and its name changed to 250SL. Though the larger engine didn’t make any more horsepower, it did offer an additional 15 pound-feet of peak torque (a total of 174). The other big addition to the car was a set of rear disc brakes to go along with fronts.

A collapsible steering wheel column was adopted this same year.

While the 250SL was an improvement over the 230SL, it was in production for less than a year before being replaced by the 280SL for 1968 .

As the name indicates, the big change for the 280SL was another displacement bump for the straight six, up to 2.8 liters. The bigger engine pumped out 180 horsepower and 193 pound-feet of peak torque and was also available with an optional five-speed manual transmission. The 280SL would prove to be the most popular of the Pagoda SLs and it stayed in production through the 1971 model year.

A total of 23,885 280SLs were built, compared to 19,831 230SLs and 5,196 250SLs.

Unlike the 300SL and 190SL, the Pagoda SL left production while still fully contemporary and attractive. Why replace it at all?

The V8 SL (1972-1989)

With V8 engines increasingly common aboard full-size Mercedes sedans during the late ’60s, it was inevitable that a V8-powered SL would appear. But in 1972 . few would have expected that the new SL (code-named R107 inside Mercedes) would define personal luxury cars for almost two decades, and over that time, be powered by eight different engines.

The story is that while it was under development at Mercedes, the R107 was referred to as der Panzerwagen because it weighed more than 3,400 pounds #151; that’s 300 or so more than the Pagoda, but still slightly short of a battle tank. Compared to the Pagoda SL, the R107’s wheelbase was 2.5 inches longer, and it was about a quarter-inch wider and a quarter-inch lower.

However, the styling, with horizontal headlights (paired round ones in North America, single squarish units in the rest of the world) and fluted rear taillights, made the new car appear much wider. Some criticized the car for being Americanized. Americanized or not, it sold better than ever.

Mercedes SL 350

Under the more mature skin, the R107 still had a double-wishbone front suspension and a new, vastly improved trailing arm rear suspension with either the Pagoda’s familiar 2.8-liter straight six or the then-new S-Class sedan’s fuel-injected 3.5-liter, SOHC V8 rated at 230 horsepower. Well, at least the rest of the world had that choice.

In North America, the only version available was powered by a 4.5-liter version of the same V8, also rated at 230 horsepower and paired with a three-speed automatic transmission. Yet during the 1972 model year (the R107’s first over here), it would still be called the 350SL.

Introduced alongside the R107 two-seat roadster was a stretched (14-inch longer wheelbase) 350SLC fixed roof coupe. The coupe, which had seats for four, would stay in production with the SL throughout the R107’s life, carrying equipment almost identical to the roadster’s.

For 1973 . Mercedes acknowledged the obvious and changed the names of America’s R107 to 450SL and 450SLC, but carried them over otherwise virtually unchanged. However a change to SAE net horsepower ratings meant the 4.5-liter V8 carried a 190-horsepower rating.

Like all cars sold on the American market that year, the 1974 450SL got a set of big bumpers to meet new government regulations and an ignition interlock system that meant the car couldn’t be started until the driver’s seatbelt was fastened.

Emissions regulations strangled another 10 horsepower out of the 1975 450SL and the ignition interlock was gone, but otherwise the car carried over very much intact from ’74. In fact the car barely changed all the way through the 1979 model year.

But 1980 brought Mercedes’ new antilock braking system to the SL #151; the first electronic ABS offered in America. Then for 1981 . the 4.5-liter engine was dropped in favor of a new all-aluminum 3.8-liter V8 rated at just 155 horsepower, and the names changed to 380SL and 380SLC. But over in Europe, a 5.0-liter, 240-horsepower version of that engine was presented in a 500SL and a few of those trickled into the United States in a developing gray market.

In 1982 . a driver-side front airbag debuted, but the car would otherwise remain virtually unchanged through the 1985 model year.

Mercedes finally did something about the SL’s lagging performance for the 1986 model year by shoehorning in a new 5.6-liter version of the all-aluminum V8 pumping out 238 horsepower and a healthy 287 pound-feet of peak torque. Beyond that, the new power was routed through a new, silken four-speed automatic transmission, and the 560SL was quickly recognized as the fastest R107 yet. Too bad it had that ugly blister on the deck lid that contained the federally mandated third brake light.

That blister would soon move to the lid’s edge and shrink in size. In the early ’80s, the R107 was already looking and feeling old. By the late ’80s, it was absolutely archaic.

The Muscular SL (1990-2002)

By the time the R107 left production, memories of the 300SL Gullwing had grown a bit creaky and indistinct. To most of the world, a Mercedes SL had always been a brawny, luxurious two-seat roadster. Whatever sportiness it offered was incidental to the car’s true mission of shuttling the rich from glamorous location to intimidating edifice and back.

The all-new R129 generation of SLs, introduced during 1989 to Europe and in early 1990 to North America, was clearly more contemporary and handsome than the outgoing car, but they were just as clearly an evolution of the species. In fact, thanks to such heavy components as a roll bar that automatically snapped up into place during an accident and a power top that used hydraulic motors to lower and raise itself with the push of just one button, the new 1990 500SL was the first SL to weigh in at more than two tons. Guess that means the L in SL didn’t stand for light anymore.

Under the chiseled wedge of the R129’s body was a densely packed structure with a double-wishbone front suspension and a rear end held up with a new five-link system that provided the most precise wheel location yet. Power came from either a new 24-valve, 3.0-liter, DOHC straight six in the 300SL, making 228 horsepower, or a new 32-valve, 5.0-liter, DOHC V8 making 322 horsepower. Both engines were all-aluminum, with the six lashed to either a five-speed manual or five-speed automatic transmission, and the V8 coming hooked to a four-speed automatic.

Despite their great weight, the power from the new engines meant these were among the quickest SLs since the original. But in 1992 . Mercedes brought along the awesome 600SL with a massive 389-horsepower, 48-valve, DOHC V12 under its hood feeding a four-speed automatic. It was very much like having two original 300SL engines under one hood.

With Mercedes’ electronic stability control, antilock brakes, adaptive damping shock absorbers and front airbags, the W129 SLs were among the most technologically intense road-going machines of that era. But despite this immense computerized competence, the R129 also brought back a measure of sporting vigor to the SL with Mercedes offering various sport packages that included items like 18-inch AMG wheels.

For the 1994 model year, the straight six was given a displacement bump to 3.2 liters. Oddly, output decreased to 217 horsepower and the 300SL became the 320SL.

Also in 1994, for no apparent reason, Mercedes renamed all of its cars by putting the letters before the numbers. So instantly the R129 variations became the SL320, SL500 and SL600. Significant changes were few however, except for the adoption of five-speed automatic transmissions by the V8- and V12-powered cars.

The Current SL (2003 – Present)

The state of the SL art now resides in what is known as R230 inside Mercedes. Using a folding hardtop like the SLK’s, the new SL is the first one since the original Gullwing not offered with a canvas roof of some sort. It’s also the quickest SL ever.

With the SLK around to cover customers who might want a six-cylinder roadster, the R230 is available only with V8 or V12 engines. At the car’s introduction during late 2001 (in Europe) and early 2002 badged as a 2003 model (in North America), the only version of the car available was the SL500 with 302 horsepower on tap from its 5.0-liter, 32-valve, DOHC V8. It also packed every technology Mercedes could conceive, including airbags to protect the head and thorax in side impacts, Active Body Control (ABC) to keep body roll in check around turns, Sensotronic electronic braking control and Distronic radar-controlled cruise control.

However the SL500 is hardly the ultimate R230. Within months of its introduction, Mercedes released the SL55 AMG, which put a supercharger on the SL500’s motor to boost power to an astounding 493 horsepower. For the 2004 model year, Mercedes unleashed the new SL600, also generating 493 horsepower but from a twin-turbocharged 5.5-liter V12.

Although the V12 offers more torque than the supercharged V8 (590 pound-feet versus 516), Mercedes claims 4.5-second 0-60 times for both cars, leading one to question why the company bothered to build them both. Mercedes insists that the visceral SL55 is aimed more at sports-car types, while the SL600, with its turbine-smooth power, is more of a grand tourer.

Nothing happened for 2005 while for 2006 Sirius Satellite Radio became a no-cost option, a tire-pressure monitor became standard and the SL600 lost its mobile phone but gained keyless starting and a heated steering wheel.

More power was the big news for 2007 as the base SL’s name changed from SL500 to SL550, indicating a new, 5.5-liter V8 engine. At 382 hp, the SL550 boasted 80 ponies more than before, dropping the entry-level SL’s 0-to-60 time to just 5.3 seconds. Other changes included the fitment of a more direct steering system, new wheels, three grille bars (versus the previous four), a deeper front airdam and a clear-lens taillight insert.

The SL55 AMG and SL600 also sported more power this year as they were tweaked to put out 510 hp each. After all that, the SL remained essentially unchanged for 2008 .

Although the style of this generation SL was wearing well, after six years it was time for an update, so for 2009 it received one. An aggressive new front end led the way as the circular dual headlights were replaced by more angular single piece units while a wider grille and dual hood bumps recalled the classic 300SL of the ’50s. As far as hardware changes, handling prowess was increased via tweaks to the steering and Active Body Control systems. The steering adopted continuously-variable ratio technology

And the SL55 became the SL63, as the force-fed 5.4-liter V8 was replaced by a new naturally aspirated 6.2-liter unit with 518 hp. The SL63 also heralded the arrival of Mercedes’ Speedshift MCT, a new multiclutch seven-speed automatic transmission that afforded lightning-quick gearchanges.

Mercedes SL 350

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