The Big, Bad, Automatic Benz That Took on the WRC - the C107

In 1978, Mercedes-Benz made the decision to expand its efforts in rally competition. But its choice of platform to enter into the World Rally Championship was, to say the least, unique.

At the time, the WRC was dominated by small sedans like the Fiat 131 Abarth and Ford Escort RS1800 — cars that finished first and second in the championship that year. Mercedes-Benz took a decidedly different route, as it had no small sporty sedan.

What it did have was a large, heavy and expensive personal luxury coupe in the C107 SLC. While the choice would seem unnatural, under the direction of Erich Waxenberger the premier 450SLC was prepared and developed over the next few seasons into a rally winner.

Mercedes-Benz 450SLC

For the 1978 rally season, Mercedes-Benz entered what were effectively production 450SLCs into a few world rally events. These cars carried the standard M117 4.5-liter V8 — a single overhead cam, 16-valve 90-degree bank producing 227 horsepower. The transmission was unusual for a rally car, as they carried the standard production 722.0 hydraulically controlled three-speed automatic.

With little else than some skid plates, extra lights and roll cage protection fitted, these cars were entered into the grueling Vuelta a la América del Sud — a 30,000 kilometer lap of South America. Matched up against those Fiats, Fords and Africa-conquering Peugeots, the luxurious automatic Mercedes-Benz coupes seems to be at a distinct disadvantage. However, at the hands of Andrew Cowan, who would later go on to start Mitsubishi’s Ralliart race team, the big coupe won the event. Co-driving in Timo Mäkinen’s 450SLC was none other than Jean Todt, future Ferrari F1 director and FIA President. Video exists of the cars competing in 1978.

While the standard 450SLC had proved unexpectedly triumphant, Mercedes-Benz was hard at work on a much improved model.

450SLC 5.0

Alongside the production M117 4.5s, Mercedes-Benz decided to up the ante on the rally effort with the introduction of the increased-capacity 5.0 M117. Now the the suffix E50, power increased to a reported 290-310, and the 5.0 ran in FIA Group 4 competition for the 1979, 1980 and (briefly) 1981 seasons.

In order to help curb the substantial weight of the 107 chassis, aluminum doors, hood and trunk lid were produced for the 5.0. The 5.0s gained large black flares, some housing wider BBS RA light alloy wheels, instead of the standard Bundt alloys found on early cars. To order to conform to FIA Group 4 rules, the engine was destroked from the production 5,025 cc to 4,973 cc. Unlike previous Mercedes V8 blocks, this one was all aluminum to help reduce weight.

Mercedes-Benz had to homologate the car in order to race, so the company created the C107.026. Ultimately, the company built 2,769 examples of the 450SLC and later 500SLC, but for 1978 the rules necessitated the production of at least 400 examples. These were obviously detuned compared to the race cars, but still packed a respectable 240 horsepower. As with the race cars, they featured aluminum bodywork to reduce weight. The automaker also had spoilers fitted, which was judged by some to be a bit shocking for the typical flagship Mercedes-Benz buyer of the time. (The owner could opt out of the spoiler, but doing so would also remove the aluminum trunk and fit a standard steel unit in its place.) Mercedes-Benz claimed the use of aluminum cut 125 pounds off the curb weight.

At the hands of Hannu Mikkola, the 450SLC 5.0 would win the Rallye Côte d’Ivoire and came second in the Safari Rally.

Mikkola would ultimately place second in the World Rally Driver’s Championship for 1979, in part thanks to the 450SLC 5.0, and the 5.0 would continue to place in world rally events in 1980, finishing third at Rally Safari in the hands of Vic Preston, Jr.

500SLC/500SL

For the 1980 and 1981 seasons, Waxenberger once again turned the wick up on the C107. Now called the 500SLC, the C107 was moved to Group 2 – Touring Cars, as opposed to the Group 4 “Special Touring Cars”. This was allowed because over 1,000 units had been produced. The M117 was now over 300 hp, with Mercedes-Benz claiming an output of 329 hp by the end of the run. The biggest change between the 450SLC 5.0 and the 500SLC was the switch from the three-speed automatic used in ’78 and ’79 to a new four-speed unit.

It also coincided with a nomenclature change at Mercedes-Benz, resulting in a 5.0 V8 for normal series production. However, while it shared the same M117 engine designation as the 450SLC 5.0, the internal structure of the engine was changed for larger-scale production.

The 500SLC went 1-2 at the 1980 Bandama (Ivory Coast) Rally with Scandanavians Björn Waldegård and Jorge Recalde, and with Mikkola driving finished second at the Rally Codasur (Argentina) and third in New Zealand. These results contributed to a fourth-place overall standing for the SLC in the WRC.

In the ultimate development of the 107 chassis, Waxenberger proposed a move to the much shorter (and lighter) SL platform. With the +2 taken out of the equation, the shorter wheelbase allowed for better response in cornering.

As with the SLC, the 500SL carried a 722.2 four-speed automatic. To lighten the car, the windows were all replaced with lexan, while the roll cage material was changed to aluminum. A large, high-rise handbrake was fitted in front of the plastic Recaro racing seats to help rotate the big Benz. That rotation would be assisted by new drivers Walter Röhrl (the standing WRC Driver’s Champion that year) and Ari Vatanen for the 1981 season, which looked like it had the potential to be dominated by the big converted convertible.

The only problem was funding. Daimler-Benz’s board called on Waxenberger to justify the budget, then promised only to deliver enough funds to run one car. Waxenberger, in a bold move, said he’d rather not run at all than only run one car and left the meeting. His wish was granted; funding to the rally program was cut for the 1981 season, leaving the ultimate development of the 500SL stillborn.

The company hasn’t forgotten the project, though, as the 500SL rally has recently appeared in a promotional video of the bellowing convertible rally car sliding through the desert, and one of the four prototypes was crashed at the Goodwood Festival of Speed with Roland Asch at the wheel during a demonstration run.

In what may be an even more unusual twist of the racing heritage of the SLC, in 1978 Affalterbach-based AMG Motorenbau GmbH entered a variant of the 450 into the European Touring Car Championship in Group 4 (and later, Group 2). Competing against the likes of the Alpina-built BMW 635CSi, Luigi BMW 3.0CSLs, Zakspeed Ford Escorts, Speiss Volkswagen Sciroccos, Eggenberger-run 320is and some trick Audi 80 GTE full works cars, the privateer entrant seemed out of place and outclassed. In short, all of them were lighter, but not more powerful. AMG took the standard 4,520 cc M117 V8 and managed to massage it to a claimed 390 horsepower for the 1980 season. Massive 11-inch wide BBS magnesium wheels were barely contained under the hugely custom flared arches, and the entire chassis was lowered several inches.

However, as no manual transmission had been homologated with the 450SLC, AMG was forced to retain the standard 722 three-speed automatic! This left the heavy Mercedes again at a disadvantage to the much lighter manual Audi, BMW and Mazda entrants. However, the AMG SLC once again showed the legendary Mercedes-Benz legacy for engineering prowess on its way out. At the Nürburgring Nore in June 1980, the SLC triumphed — a four-hour war of attrition saw the sole Mercedes-Benz (in the hands of Clemens Schickentanz and Jörg Denzel) emerge as the winner. It was the only time a C107 would win in the European Touring Car Championship, but it pointed the tri-star towards a return to circuit racing and an end to its self-imposed ban following the 1955 Le Mans crash.

[Images and Source Material: Daimler]