At start of the 1990s, after the introduction of their two-seater grand-tourer R129 SL and the Mazda MX-5, Daimler-Benz set out to create a new compact roadster, positioned below the SL. By late 1991 under Bruno Sacco, the first design sketches were drawn and twelve 1:5 scale models being built in the first half of 1992. By the middle of the year, five of them were proposed again in full-scale. In early 1993, the final design was selected and approved by the board, with the German design patent being filed on September 30, 1993. On April 22, 1996, the new production SLK-Class, based on the R170 platform was introduced at the Turin Motor Show. SLK 230 Kompressor launch model became a competitor to the Porsche Boxster and BMW Z3. It was powered by a 193 hp 2.3 L supercharged straight-4 engine and a choice of automatic transmission or 5-speed manual transmission. The SLK was a modern incarnation of the 1950s Mercedes-Benz 190SL by returning to four cylinders and a 94-inch (2,400 mm) wheelbase. Worldwide sales hit 55,000, over double the entire nine-year production of 190SLs, and between 1996 and 2004, over 311,000 SLKs were sold. The last was completed on April 7, 2004.
The roof design, marketed as the Vario-Roof, consists of a folding steel hard top divided in half along a transverse axis. Both halves are linked by a kinematic mechanism which is locked securely when the roof is closed. At the touch of a button on the centre console, a hydraulic system with five cylinders controls the fully automatic folding process in which the boot lid is also integrated. It opens by tipping to the rear so that the two roof halves have sufficient movement to pivot backwards as the roof opens; the roof sections then position themselves on top of each other and fold into the boot. If the roof is to be closed, the same sequence of movements is performed in reverse order. The hydraulic system stows the roof in the upper section of the boot. A plastic roller blind separates the roof from the luggage space below, a volume with a capacity of 145 litres in the first-generation SLK. With the roof closed, the load volume increased to 348 litres (12.3 cu ft). Two fixed roll-over bars behind the seats worked with the A-pillars to form an integrated system offering a high degree of roll-over protection.
The steel roof provides added protection, which is normally found in a coupe, but with the flexibility of a convertible at the same time.
In 1997, development on updates to the R170 began and by early 1998, design work on an updated SLK was completed and patented on February 2, 1998. In February 2000, the SLK received a facelift which included new front and rear bumper designs, body-coloured side skirts and the introduction of new wing mirrors incorporating indicators. The range was expanded to include a new entry-level model SLK 200 Kompressor and a new V6 in the SLK 320 with M112 E32 engine. Technical improvements included the addition of Electronic Stability Program (ESP) and a new 6-speed manual transmission. A stabilizer bar was added to the rear and the front one was reinforced. A 3.46:1 axle was added for the manual shift SLK, and the fuel tank grew from 12 to 14 gallons.
In 2001 a new AMG model was added, with a 349 hp (260 kW) supercharged version of the 3.2 L V6. This SLK 32 AMG was the most powerful R170 SLK, and was a direct rival of the BMW M Roadster and Porsche Boxster S. It was only offered with the newly engineered five-gear "SpeedShift" and boasted 35% quicker automatic shifts. All engines were hand built by AMG by an individual engineer. The SLK32 AMG's engine has two spark plugs per cylinder for maximum combustion and was fitted with an intercooled Lysholm-type twin-screw supercharger. Brakes became 13.15 in (334 mm) diameter, upgraded from the standard 11.8 in (300 mm) items. AMG production ran between Aug 2000 and March 2004. Only 4,333 were built in total, of which 979 were retained for Germany, 2,056 exported to the USA, and 263 to the UK and are a very rare find today.
In July 2004 a special edition was launched prior to the replacement with the new R171 SLK in 2005. The R170 lived on as the Chrysler Crossfire until 2008, sharing substantial elements of the SLK including engines and interiors.
R170 range summary
Not all models were exported to all markets.
SLK 200 (1996–2000) – 2.0 L (1998 cc) 136 bhp (101 kW; 138 PS) I4
SLK 200 Kompressor (2000–2004) – 2.0 L (1998 cc) 163 bhp (122 kW; 165 PS) I4 supercharged engine, 0–60 mph in 7.8 seconds, top speed of 138 mph.
SLK 230 Kompressor (1996–2000) – 2.3 L (2295 cc) 193 bhp (144 kW; 196 PS) I4 supercharged engine
SLK 230 Kompressor (2000–2004) – 2.3 L (2295 cc) 197 bhp (147 kW; 200 PS) I4 supercharged engine, 0–60 mph in 6.9 seconds, top speed of 148 mph.
SLK 320 (2000–2004) – 3.2 L (3199 cc) 218 bhp (163 kW; 221 PS) V6 engine, 0–60 mph in 6.9 seconds, top speed of 152 mph.
SLK 32 AMG (2001–2004) – 3.2 L (3199 cc) 349 bhp (260 kW; 354 PS) V6 engine, 0–62 mph in 5.2 seconds.