They were the two greatest marques in the vintage years of sports car racing, yet rarely met directly on the track. Bill Boddy assesses which had the edge — Bentley or Mercedes-Benz
When I was growing up I found it very difficult to know exactly whether my teenage allegiance lay more to Bentley or to Mercedes-Benz, both makes then prominent in sportscar racing.
At the age of 14, with the presumptuous assurance of a motor-mad schoolboy, I wrote a letter to The Autocar about supercharging, suggesting that the Mercedes method of blowing air into the carburettors was superior to sucking mixture from them. This was duly published over my initials WB. Mercedes-Benz saw this as a possible means of selling one of their fabulous supercharged 36/220 sportscars to someone they assumed to be a potential customer, so they obtained my address from the magazine and invited the letter-writer to take a trial run. I duly arrived at Grosvenor Street, the London headquarters of the German company, wearing my school cap. I produced the invitation and was asked whether my father was coming soon. “No,” I replied, “he was killed in the war”. It dawned on the astonished salesman that it was me who had written the letter. But Mercedes, as I was to discover in later years, was efficient to a degree. The massive German manager was consulted, he eyed me and the salesman returned. He then told me that I would be shown how one of their cars performed. Soon a test driver stopped an open 36/220 outside, I got in, and we attained about 100mph along the Barnet Bypass. My first cause to respect the Three-Pointed Star had occured.
Against that, Bentley cars, the 4 1/2-litre fours and 6 1/2-litre Speed Sixes, were dominating Le Mans and doing exceedingly well at Brooklands, and I had plenty of reason for pro-British enthusiasm. Which has prompted this attempt to assess which of these well-known makes was the more successful in the field of top-class sportscar racing.
Mercedes had been making cars long before WO had begun racing DFPs and, by 1919, making the 3-litre Bentley. The German cars achieved some notable racing successes, topped by that devastating disposal of the previously invincible Peugeots with the 1-2-3 finish in the 1914 French Grand Prix at Lyon on the eve of the war.
The impressive 36/220hp Mercedes-Benz with its Teutonic vee-fronted radiator, those triple external exhaust pipes protruding from the offside of the long bonnet and a low-hung chassis, had been preceded by the four-cylinder 12/40hp model of 1925, its supercharging innovation no doubt founded on war-time aero-engine research. The six-cylinder sportscars followed, in the sequence 24/100, 33/180, 36/220 and 38/250hp.
The 33/180 had a 6.3-litre engine and was described as the first genuine 100mph touring car. The later 36/220 model (which in S for Sports form became the best known) had a 6.8-litre engine of the same type; it created a sensation when shown at Olympia in 1927. It had a wheelbase of 11ft 8.8in, a dry multi-plate clutch, a four-speed gearbox and a 27-gallon petrol tank. The four-seater cost £2300. After Motor Sport tested one in 1930 the driver exclaimed: “Words fail me; this has been the most amazing motor car it has been my good fortune to drive.”
The 38/250 had the same engine enlarged to 7.1 litres, with a vertical twin-vane Roots supercharger driven from the front of the crank, geared to run at three times engine speed. This blower was engaged by a clutch when the accelerator pedal was fully depressed, to gain extra power above the unboosted 140bhp at 3200rpm for better acceleration. Since it blew through the carburettor, the petrol tank and carburettor float chambers had to be pressurised as well. The siren scream when the supercharger was in use added to the awe with which ordinary motorists regarded these big Mercedes. This powerful car with its higher chassis was produced in SSK (K for short-chassis) and SSKL (L for Light) versions. The SSKL had a bigger, or ‘elephant’, supercharger giving 10 lbs/sq in boost, a special camshaft, drilled side-members and a wheelbase of 9ft 8.8in.
The 4 1/2-litre Bentley was an enlarged edition of the 3-litre, and the Speed Six had a 6.6-litre six-cylinder engine with the same fixed four-valve head but a sophisticated triple-eccentric drive for its overhead camshaft. The crankshaft had eight bearings and there was magneto and coil dual ignition. The short chassis had a wheelbase of 11ft 1.25in, a 25-gallon petrol tank and sold for £1450.
I have driven the ex-Sir Malcolm Campbell 36/220S Mercedes-Benz, GP10, the 1929 38/250 TT-winning Mercedes-Benz and a Bentley Big Six, all excitingly memorable experiences. But what of the racing comparison?
Racing resumed in Germany soon after the war had ended, and Mercedes had many successes in races and major hillclirnbs. The first German Grand Prix was held in 1926, but the 1927 GP was for sportscars only, and a truly enormous crowd at the new Niirburgring saw seven Mercedes-Benz, which were virtually standard 36/220s, start in the event. They finished 1-2-3. Otto Merz, former chauffeur to Archduke Ferdinand, was the winner at 63.38mph over the difficult course, Christian Werner next and Willi Walb third.
Caracciola and Rosenberger were 1-2 in the follow-up sportscar race, Ruth winning at 4.6mph faster than the old s/c Mercedes of Werner in the racing car class. Prior to this, Bentley had won at Le Mans in 1924 (at 53.78mph), and again in 1927, at 61.35mph, with its 3-litre cars.
In 1928 Mercedes were again 1-2-3 in the German GP at the ‘Ring, where the heat played havoc with tyres. Caracciola and Werner won at 64.56mph, from Merz and Wemer/Walb. Private owner von WentzelMosau, a rather wild driver, won the Wisbaden races in his 36/220, and Prince Hohenlohe the 50km Kesselberg hillclimb. Mosau was second in the GP de la Baule, and Caracciola, now in an SSK Merc, was quickest up Friburg. Away in Buenos Aires the 12hour Production Car race went to a 3-litre Bentley. Over here, H F Clay, a versatile amateur, won the sportscar class at Shelsley Walsh.
One has to try to assess how these results stack up against the major Bentley performances of 1928. At Le Mans the British marque had its third victory when ‘Bentley Boys’ Woolf Barnato and Bernard Rubin won at 69.11mph, while in the Essex MC’s Six-Hour race at Brooklands, Birkin and Dr Benjafield were third in a 4-1/2-litre. The year 1929 opened well for Mercedes-Benz when it nearly won at Monaco, on a street circuit unsuited to a big and heavy car. In this racing car contest Caracciola was defeated only because he required a two-minute pit-stop for can after can of fuel and a wheel change, following a duel with Williams’ more suitable GP-type Bugatti 35B. Rudi was eventually also vanquished by
the Bugattis of Bouriano, but it was an epic drive, with Rudi beating four other 35Bs. Perhaps we should not regard a stripped SSK as a sportscar.
Rudi then had another great drive in a works 38/250 in the Ulster TT, when cars had to be close to catalogue specifications. In heavy rain he whittled down his handicap and won magnificently, at 72.82mph for the uncomfortable 410 miles on a by no means easy circuit. Earl Howe used this car to win the sportscar class at Shelsley Walsh, and second to his Lordship was ‘Scrap’ Thistlethwayte in his 36/220, with which he had also won the 100-mile race on Southport’s sands. In the Irish Grand Prix he had led Birkin’s blower 4’1/2 Bentley for the first two hours, having beaten the Bentleys in practice, before the head gasket gave out. At St Moritz the SSKs took a first and second, and a 36/220 won from a lady driver’s 38/250, von Brauchitsch making HD in a 38/250 in the `touring car’ class. And there were more hillclimb best times.
Bentley’s 1929 highlight was the wonderful 1-2-3-4 finish at Le Mans, with Bamato/Birkin first, having averaged 73.62mph in a Speed Six, followed by three 4 ih s. The JCC `Double-Twelve’ produced a second for S C H Davis and Sir Ronald Gunter in a 4-1/2, and then the Speed Six won the BARC Six Hours for Bamato and Jack Dunfee. Commander Glen Kidston used the Speed Six to make best race average in taking second place in Dublin’s Irish GP, Birlcin’s blower 4-1/2 third, but the Ulster TT was a Bentley no-go.
In what I regard as the end of the vintage period, 1930, Bamato and Glen Kidston achieved Bentley’s fifth Le Mans victory, with Watney’s sister car placed second. This was the dramatic occasion when Sir Henry Birkin went flat out to attempt to break Caracciola’s Mercedes-Benz, passing it at top speed on the verge in his blower 4-1/2 Bentley. Eventually the Mercedes came in and retired. The cause was claimed to be a flat second battery, preventing them from refiring the engine on the starter as the rules required. But cynics suggested that the dynamo or the engine had failed, possibly because Birkin had caused Rudi to keep the supercharger in use for too long. Not surprisingly, soon after Birkin had gone in front, a tyre tread flew off and he was afterwards in frequent tyre trouble, finally retiring. The Speed Six then continued to harry the Mercedes until its retirement during the night W Bentley objected when Birkin supercharged his 4 1/2-litre engine and must have thought the Mercedes system ridiculous, but I wonder whether this episode made him a little less critical.
Caracciola was barred from entering the 1930 TT after Malcolm Campbell protested that his oversize blower was non-standard and thus ineligible for a production car race. But the German ace then won the Phoenix Park GP with another top-class drive in the rain. In spite of a multiple spin at speed, he won the race at 85.88mph over 300 miles, setting the lap record at 91.3mph. Earl Howe was fourth and Campbell sixth in the 38/250s, separated by Birkin’s At Pau, Birkin tackled the racing cars in a stripped blower 4 1/2 Bentley to be placed second.
Goffredo Zehender unsuccessfully entered an SSK in the 1931 BRDC ‘500’, a race in which Bentleys often did very well, but those cars had trackracing bodies, so really fall out of the scope of this assessment Although beyond the ‘vintage’ era I cannot resist describing Caracciola’s win for Mercedes in the 1931 Mille Miglia, that quite unique road race, in which he drove without team-mate Sebastian taking over, averaging 62.85mph, including tyre, fuel and control pauses. He deserves being applauded for this precursor to Moss’s never-to-be-surpassed feat of winning the event in 1955, navigated by Denis Jenkinson’s roller-blind map. Moss must be given every credit for having made the fastest winning speed ever in this epic road race, an incredible 97.9mph. Bentley never took part in this Italian marathon. Winged-B or Three-Pointed Star? I am not taking sides, but one avid M-B enthusiast used to remind us that they met in only three international events in vintage times, the 1929 TT and 1930 Laster TT and Le Mans (score: Mercedes, two; Bentley, one) and that at Le Mans in 1930 the lone ill-fated Mercedes was up against six Bentleys. It was also the only M-B retirement in these major races. After 1930, Bentley’s official racing programme ended but Mercedes continued, winning repeatedly until the end of ’55 with those almost unbeatable racing and sportscars, which people (but not me) will call ‘Silver Arrows’.
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