If you’re a little bored with seeing this particular 300SLR in the pages of Octane, then we apologise. Yes, it was on the cover of issue 17, and it’s appeared more than once in the mag this year as part of all the brouhaha surrounding Mercedes’ 50th anniversary win of the Mille Miglia in 1955. But after this feature, chances are it won’t be appearing in Octane or any other mag for a long time to come. Now that DaimlerChrysler’s new multi-million-Euro museum is nearing completion, ‘722’ is about to be retired from front-line PR service to go on permanent display. It’s too valuable to be risked on events like the Mille any longer, says the company.

Forgive us, then, for indulging in one last tribute to what’s arguably the most famous racing car in the world. It is, after all, the ‘signature’ car of Octane columnist Sir Stirling Moss, who drove it to victory in 1955 and who has been its most regular pilot in recent years. DaimlerChrysler’s offer of a ride – and, who knows, maybe even a drive? – in 722 before it is mothballed, possibly forever, was too good to pass up.
Stirling Moss says he can remember the precise moment at which he was won over to join the Mercedes team for 1955.

‘I went for a try-out in the middle of winter – it was Hockenheim – and I drove this new W196 Formula One car, and because it had inboard brakes you got dust on your face. I used to wear large goggles and so I had a “panda face”, with white eyes and black face. I got out of the car and was looking around for a bit of rag. Up comes a mechanic, clicks his heels, bends forward – there’s a bowl of water in his hands, but not just a bowl of water; it’s hot water, and in his hand is a piece of soap, and over his arm is a towel. And I thought, my God, this is something.’

The car that Moss had been sampling that winter’s day at Hockenheim was the W196: the open-wheeled, grand prix version of what would become the 300SLR. Juan Manuel Fangio won two World Championships for Mercedes in ’54 and ’55, driving the W196 F1 car – but it was Moss who dominated with the sports-racer 300SLR in 1955. Besides the Mille Miglia, which he won at an all-time-record average speed of 97.960mph (157.651kph), Moss also came first in the Dundrod TT (with John Fitch) and the Targa Florio, co-driven by Peter Collins. On both occasions he beat Fangio into second place.

But it’s for the Mille Miglia that Moss and his SLR will always be remembered. Few people know that Moss’s SLR is chassis number 0004; everyone recognises its Mille Miglia race number of 722, signwritten in bold Roman numerals like the identity of a Tiger tank. The impressively large number simply signifies that Moss and co-driver Denis Jenkinson were due to start from Brescia at 7.22am on May 2, 1955.

The start number is not the only militaristic feature of Moss’s SLR. The silver-painted, aerodynamic body recalls the bare-alloy and silver-doped fighter-aircraft prototypes of the early 1930s, and the twin exhausts that exit halfway along the offside are irresistibly reminiscent of gun barrels. But the greatest similarity with aircraft is in the engineering. Mercedes capitalised on its wartime aero-engine experience by equipping the 300SLR with direct mechanical injection into each cylinder.

The SLR engine is a marvellous thing. Not a beautiful one, draped as it is in an Alien-like cradle of pipes and hoses, but technically ingenious and superbly made. Like a pre-war Bugatti straight eight, it has two four-cylinder integral heads and blocks mounted on a common crankcase, with a built-up crankshaft running in roller bearings. The crankcase is made of aluminium alloy, the blocks of Silumin alloy, and the valves are both opened and closed mechanically by twin camshafts.

More remarkably, drive to the clutch is via a shaft running from the mid-point of the engine, and the propshaft then passes between the driver’s legs en route to the rear transaxle. The clutch pedal is therefore a good 24 inches to the left of the brake and accelerator, which are crowded together on the right of the transmission tunnel. This causes some involuntary amusement when, the first time I come to brake, my enormous size 13 right foot depresses both brake and throttle simultaneously. My, how the DaimlerChrysler people laughed, as their impossibly valuable piece of history disappeared towards the horizon...

Tempting as it is to describe how I thrashed 722 around the Mercedes test track, stirring memories of a youthful Moss and causing elderly Neubauer-lookalikes to tip their Homburgs in tearful homage, the truth is that no outsider below the rank of F1 pilot is allowed to drive 722 in anger these days. My own experience was limited to a few low-gear trundles up and down the infield (albeit rather further than expected – see above).

But workshop manager Gert Straub is one of the hallowed few permitted to let 722 off the leash, and Denis Jenkinson’s seat beckons. Privilege though it is, I’m secretly thankful we won’t be doing more than a few laps of the test track, because Jenks’ narrow bucket seat – trimmed, like Moss’s, in kitsch 1950s checked cloth – would be more at home in a pedal car.

Push in the ignition key to activate the fuel pumps, turn the mag’ switch on, and press the starter. The engine’s fuel injected, of course, so it ignites immediately. My God, it’s noisy! Fantastic, thrilling, exhilarating, but so noisy! Sitting aft of the engine is like standing alongside a Messerschmitt 109 as the pilot warms up the oil. Raw, mechanical, shrieking – it’s all of those things, but most of all it’s just bloody loud.

From my shopping-trolley manoeuvres I know that the clutch is sharp-ish but not too heavy, and that the gear lever moves with the solid, mechanical feel you’d expect of a 1950s Mercedes. The polished gate is a work of art, with a tactile little lock-out lever to prevent you selecting reverse by mistake. You also have to depress a button on top of the gearknob in order to move into the first-reverse slot.
Now, Gert Straub takes his responsibilities seriously, and that means ensuring that 722 is ready for the kind of no-nonsense treatment that Moss and, on the Mille retrospective this year, Jochen Mass are likely to dish out. The car is already thoroughly warmed, so he just points that long silver nose out of the pitlane, and floors it.

Jeeeeeez! This car is not just loud as an Me109, it accelerates like one too. With a power-to-weight ratio similar to that of a Lamborghini Countach, it just squats on its haunches and goes – whatever speed you’re doing. And it’ll keep on going to nearly 180mph, for as long as the driver can handle it: on the long, straight sections of the ’55 Mille, Moss regularly saw over 170 with the engine nudging its 7500rpm red line.

Noise level apart, 722 is a reasonably comfortable machine in which to burn up the kilometres. Inboard-mounted drum brakes help keep the unsprung weight down, which benefits the ride – although they were also responsible for those ‘panda faces’ mentioned by Moss, since the brake dust is sucked straight through the cockpit. Disc brakes would have been more effective but drums did the job, even when the friction material had worn away and the aluminium backing plates were hard against the drums’ inner faces, as they were by the end of the ’55 Mille. Moss remembers that their biggest drawback was a habit of locking on when the linings crazed: Mercedes’ solution (but not on 722) was to install buttons in the cockpit, one for each front wheel, to inject a drop of oil into the affected drum at crucial moments.
Those inboard brakes probably help explain why the SLR’s steering is remarkably light, even at walking pace. I can personally vouch for that, if not for the fact that it is also superbly precise at race speeds. Hanging the gearbox at the back of the car gives a front/rear weight distribution of about 42/58 percent, and the low centre of gravity means that the rear wheels’ single-pivot swing axle rarely causes anxiety unless the driver is exceptionally careless. Nevertheless, when spectators on the Mille Miglia occasionally threatened to block Moss’s path, he would deploy the novel technique of wiggling the steering wheel violently so that it looked as though he were losing control; sometimes this encouraged the crowd to pull back – ‘but not always’.

Inevitably, there were times when even Moss was caught out. Four times on the Mille Miglia, in fact. On the Dundrod TT, a rear-wheel blow-out ripped the magnesium-alloy body apart but, again, the damage wasn’t enough to prevent Moss’s car finishing, and winning. And on the Targa Florio in October ’55, Moss left the road, skidded down a slope and ended up in a field. The Mercedes mechanics patched up 0004’s damaged radiator and Moss’s co-driver Peter Collins rejoined the race – adding a few more scars on 0004’s bodywork along the way. Needless to say, the Moss/Collins partnership won the event, ‘despite all the efforts of Stirling and me to smash the car up’, as Collins said later.

Despite its eventful competition career, 722 is believed still to be remarkably original, and to retain its original spaceframe chassis. As time passes, that originality becomes increasingly precious, which is one reason why 722 is now being mothballed and the baton of its PR duties passed on to sister car 658, Fangio’s mount on the 1955 Mille Miglia.

‘To be honest, I feel that 722 has been over-exposed in recent years,’ says DaimlerChrysler Classic’s manager Josef Ernst. ‘In future, it will be used much more sparingly. I’m not saying that it will never come out of the museum again – but the way the cars are to be displayed means that moving it will not be so easy as it is in the present location.’

The journalists, racing drivers and assorted hangers-on who have inveigled themselves into the hot seat of 722 in the past can therefore count themselves extremely fortunate. As do I, even if my experience lasted more like 1000 yards than 1000 miles. But hey, a drive is a drive, right? It’s something to tell the grandchildren – if I ever have any.