2004 Mercedes-Benz SLK (R171)

General information & model overview

Body & dimensions

Engine specifications (launch years)

Drivetrain & transmission

Chassis, equipment & new features

Performance (approximate)

Image source: Wikimedia Commons

What the 2004 SLK (R171) is

The 2004 Mercedes-Benz SLK is the second generation of the compact hardtop roadster. Unveiled at Geneva in 2004, it replaces the R170 with a longer wheelbase, wider body, faster-folding Vario roof, higher structural stiffness, and the new Airscarf comfort system. The “Formula One–inspired” pointed nose defined the car’s public image for the rest of the decade.

Why R171 was a step change

1. Structure and size

Mercedes increased high-strength steel content and claimed large stiffness gains with the roof down. The car is longer and wider than R170, improving cabin space and crash structure while remaining a two-seater.

2. Roof packaging

A rotary-pivoting rear window and redesigned stack cut operation time to about 22 seconds and freed boot space when the roof is stowed — a direct answer to R170 luggage complaints.

3. Airscarf

Neck-level heating made open-top driving viable in cooler weather and became a hallmark SLK feature carried into the R172.

Image source: Wikimedia Commons

Powertrains of the launch years

Early cars centred on the supercharged 1.8 four, the 3.0 and 3.5 V6s, and the 360 PS SLK 55 AMG V8. The SLK 350 with a six-speed manual was widely reviewed as the driver’s choice in the non-AMG range. The 55 AMG brought a true V8 soundtrack and sub-5-second acceleration to the compact roadster class.

The limited Black Series (from 2006) raised output near 400 PS, fitted a fixed carbon roof theme, wider arches, and track-oriented suspension — a rare extreme branch, not the volume car.

Ownership notes for early R171

1. Pre-facelift identification

Front bumper, mirrors without later LED arrows, and lower-output 272 PS SLK 350 engines mark early cars. See the 2008 facelift entry for the later specification set.

2. Mechanical watch points

M272 V6 balance-shaft and timing issues are documented industry-wide on related engines — verify history. Supercharged fours need correct oil and supercharger condition. Roof drains and Airscarf blowers are inspection items unique to this product type.

3. Market role

By 2008 cumulative SLK family sales passed half a million units. Early R171 cars are now accessible used roadsters; condition of roof and electronics dominates value more than colour.

Formula One nose and second-generation packaging

The pointed front end, with its pronounced grille and air intakes, was marketed as Formula One–inspired and gave the R171 an aggressive face distinct from the elliptical R170. Underneath, the car grew in track and wheelbase to improve stability and cabin space. High-strength steel content rose, and Mercedes published large percentage gains in roof-down torsional stiffness — important because hardtop roadsters are structurally challenged when open.

Airscarf as a product invention

Warm air ducted from the headrests to the neck sounds like a comfort gimmick until used on a cool evening. It extends the open-top season and reduces the need to run the cabin heater hard with the roof down. The system includes blower and duct hardware that can fail or clog; function checks are part of any serious R171 inspection. Later generations kept the idea because customers expected it.

SLK 55 AMG and Black Series extremes

The standard 55 AMG put a 5.4-litre V8 into a compact roadster with AMG brakes, exhaust, and bodywork. Independent tests recorded mid-4-second 0–60 mph runs. The Black Series removed the folding-roof practicality in favour of a fixed carbon roof theme, wider bodywork, and about 400 PS — a rare track-leaning special, not a volume SKU. Most owners and most encyclopedia interest still centre on the regular folding-roof cars.

Legacy

The 2004 R171 established the modern SLK template: stiffer structure, Airscarf, F1-nose design, and a V8 AMG peak. It is the generation that made the compact Mercedes hardtop roadster a mature global product rather than a first-generation novelty. Durable facts: R171 from 2004, Bremen, Vario roof ~22 s, Airscarf debut, engines from ~163 PS four to 360 PS V8 AMG before the 2008 power bumps.