There is little need to mention the triumphant return to racing - of Mercedes- Benz with the 300SL. The team, it will be remembered, had an incredibly successful season in 1952, which included the victory at Le Mans. After that, the cars were withdrawn,from competition while their makers prepared to enter the Grand Prix sphere, and we thought we had seen the last of the silver coupes.
How exciting it was, therefore, when it was announced that the engine. power had been greatly augmented by the adoption of direct fuel injection, and that the model was to be placed on the market at a not unreasonable price. Obviously, this must be one of the most potent production road cars ever sold, and so I was delighted when the manufacturers offered to lend me one for a week's hard motoring.
The basis of the 300SL is an immensely rigid tubular frame. This consists of a very large number of steel tubes, and extends into the scuttle and also embraces the engine, which is considerably inclined towards the near side to reduce its effective height. In front, there are forged wishbones of unequal length with helical springs, and an anti-roll torsion bar. The Z.F. steering gear operates through a three-piece track rod, which has a hydraulic damper to avoid road shocks and shimmy.
Behind, there are swing axles, also with helical springs, and the final drive is a hypoid bevel. The half shafts are enclosed in tubular housings,) which pivot on the differential casing, and there is one universal joint for each side. The
brakes are hydraulic, with a vacuum servo, and operate in bimetal drums with turbo fins. A shoe width of no less than 3t ins. has been chosen.
The engine is a six-cylinder with a single chain-driven overhead camshaft. The six separate inlet ports each have their own ramming pipe, all of which are fed from a large gallery with a single throttle at its forward end. The exhaust system is on the same side, but the welded-up manifold sweeps downwards, away from the high mounted air intake system, and a shield avoids heat transference.
On the near, or lower, side of the engine is the fuel injection pump, which is driven by a shaft and gears from the front of the crankshaft. The injectors are in the block, and the sparking plugs are in the head, directly above them. The tank for the dry sump lubrication is also on this side, and there is another tank for water on the offside.
The radiator block is mounted low down .in front, and has an oil radiator alongside it. The wide bonnet is literally full right up of machinery, and two slIght bulges are, in fact, necessary to clear the valve cover and the induction manifold.
The body is, perhaps, the most typical feature of the car. To reduce the difficulty of entering the seats, which are low down between the tubes of a space-type triangulated frame, the doors of the coupe body include most of the roof. This is an extremely effective solution, and the frame is covered in and padded. There is quite a useful luggage space behind the seats, for which a fitted suitcase can be supplied. The tail locker conta,ins the spare wheel, and there is room for odds and ends here.
Before entering the car I paused to gaze at'its really lovely lines. I then operated the ingenious retractable door handle, and the gull door rose on its counterpoise springs. Folding the special steering wheel out of the way, I slipped easily. into my seat. (For a lady to enter the 300SL, a. delightful display of nylon is called for, which I do not regard as a disadvantage!) Anyway, once I was installed, I marvelled that at last a car had been made with every control in the right place.
The cloth upholstered seats are completely comfortable, and positively locate the driver and passenger. The central remote-control gear lever falls under the right hand (L.H. steering), and the wheel is well away from one's legs, so that a heavy coat can be worn if desired. AlI round visibility is first class, and although my head was close to the roof, I was never conscious of this.
On moving off, one applauds the clutch, which succeeds in being very positive without being fierce. The gearbox is light in action a,nd has effective synchromesh on all four speeds. Too many sports cars lack synchronization on bottom gear, which is really the ratio for which one needs it most. The indirect gears are not completely silent, but their slight whine is not really obtrusive.
The acceleration is so tremendous that it is almost beyond belief. It is not so much that one has 240 b.h.p. to play with, but that the torque curve is exceptionally flat. The gear ratios. are ideally chosen with this in mind, and anywhere between 3,500 and 5,500 r.p.m. the surge of power seems virtually constant. With most cars, the acceleration falls off when top gear goes in, but this one continues to leap forward. To take three times at random, imagine a comfortable closed car that can accelerate from 0 to 60 m.p.h. in 7 secs., 0 to 100 m.p.h. in 16.2 secs., or 0 to 120 m.p.h. in 25.8 secs.! I agree; it's fantastic!
As regards the timed-both-ways maximum speed, my car had the lowest of the three alternative gear ratios. In recording a mean of over 140 m.p.h., I had to take the engine up to 6,250 r.p.m. in top. This is obviously well past its peak, and I am confident that one could exceed 150 m.p.h. with a higher ratio. For British roads the one fitted is certainly the best, but I would like to try the "high cog" to record a genuine century and a half, at some future date.
The performance figures could not be achieved unless the traction was exceptionally good. The independent rear suspension helps greatly in this, and two exactly equal black lines are left by both wheels when getting off the mark. I did not treat the clutch and gear lever brutally, so a ruthless driver could possibly better my times.
Fuel injection pays dividends in giving instant response to the throttle, and at the other end. of the scale, it allows the car to accelerate in top gear from little more than walking pace. No luxury limousine has a more flexible power unit. The engine is quiet and smooth when cruising, but takes on the "hard" feel of a racing unit when really extended. The exhaust is at all times virtually inaudible, which is astonishing to say the least.
In spite of its short wheelbase of only 7 ft. 10 ins., the Mercedes-Benz is very comfortable indeed. The springing is definitely soft, but there is no pitching. Even when driving a1t 140 m.p.h. over bumpy roads, one's head never touches the roof.
To drive this car as a fast road vehicle requires only the skill that very high speeds will always demand. To drive it as a racing car, on the other hand, exacts a somewhat special technique. Very few drivers, I think, would be at home in it without a good deal of practice, and I admit that this applied to me. Once acquired, the knack is difficult to put into words, but I think it goes something like this.
Most of us enter our corners too fast, because we are accustomed to driving cars that lack engine power, and so we need the speed to initiate a drift. The 300SL has high cornering power, but excessive speed causes sudden rear end breakaway. The exceptionally high geared and hydraulically damped steering is heavy when used violently, and so one tends to over-correct which causes a series of untidy skids.
The right method, it seems, is to begin the corner a little slower and achieve a drift by using a great deal of power. Handled thus, the machine fairly rockets out of the bends, which is, after all, the object of the exercise. More than almost any car, the Mercedes-Benz responds to a good driver, but in the hands of an indifferent one it could be dangerous, and should never be sold to a beginner.
A man should gain experience in 100-120 m.p.h. cars before being let loose in this projectile. The brakes are immensely powerful and do not fade, but once again practice is necessary before one is at home with them. This is due to the vacuum servo, which gives an unusual feeling to the pedal. As soon as I had become accustomed to them, I realized that these brakes have no vices and can be used hard and continuously without diminution of their power. It is, however, possible to lock the wheels easily at 140 m.p.h., with all the drama which that entails. The brakes, in fact, are on a par with the 240 b.h.p. engine, and should be used with similar discretion.
The whole car is really beautifully constructed and finished. One hears no rattle or drumming, and a remarkable lack of wind noise is apparent. There is an elaborate system of heating, ventilation and demisting, and the front window panels also turn. The main door windows do not open in the ordinary way, but may be instantly detached and carried in an envelope in hot weather.
The aerodynamics are such that this does not cause a draught. Three small criticisms concern-the instrument lighting, which is too bright; the headlamp high beam indicator, to which the same applies and the speedometer, which is regrettably optimistic. Surely no car needs a fast speedometer less than this one!
The Mercedes-Benz 300SL is a car of beautiful appearance and almost incredible performance. Its construction and finish are of the very highest class, and its whole design represents a technical tour de force. It has perfect traffic manners, and the sheer joy of handling it on the open road has to be experienced.
