[Vitesse]

Roger and Ray:
Right and right! There were indeed eight W196s at Monza and I turned up this in Setright's Grand Prix Car 1954-66:

"Mercedes-Benz ... had settled on three alternative wheelbases for their cars and the medium and shorter versions were taken to the Nurburgring in July 1955 for comparative trials. The differences resulting from the apparently minute changes of 2.5 inches are astonishing: the times of four different drivers show that the shortest car was faster but more difficult to drive than the medium-wheelbase version. At a time when the fastest recorded lap of the Ring had been 9min 43.2sec (87.5mph) in a Mercedes-Benz W163 driven by Lang in practice for the 1939 German Grand Prix, Fangio, Moss and Kling, the principal team drivers for 1955, and engineer Uhlenhaut drove the two cars with the following results:

wheelbase: 87.5 inches 85 inches
Fangio 9min 38.8 sec 9min 33.3 sec (=88.6mph)
Moss 9min 41.2 9min 35.7
Kling 9min 47.0 9min 49.0
Uhlenhaut 9min 51.8 9min 55.6

Note how both Fangio and Moss were 5.5 seconds faster in the 85-inch car, while Kling and Uhlenhaut were slower.

As a result of these tests it had been decided that the long-wheelbase car was too cumbrous for road circuits and that although the 85-inch version was fastest it was too hard to drive, involving the pilots in strain that was too severe to endure throughout the the three hours involved in a full-length Grand Prix. Accordingly the car with medium wheelbase and inboard brakes was chosen as the basic road-racing vehicle. At Monza, however, Fangio was given one of the long-wheelbase cars to try with the aerodynamic body that had not been seen in competition since the Italian Grand Prix of the previous year; for although unofficial practice had revealed that the medium-length chassis with full streamlining would be a good combination, it was found that the old original long-chassis car was undoubtedly best for handling on the banking, especially after an experimental extended nose had been added to prevent a tendency for the front end to lift at high speed.

Moss having found the streamliner very much to his liking on this circuit, he was provided with one, within two days. This was typical of the organization and power of the Mercedes-Benz racing division; their high-speed transporter was despatched post-haste from Monza back to Stuttgart, where it collected another long-chassis car, one that had not been used since Monza 1954, and brought it down to the Italian circuit, while another chassis was made and fitted with one of the 1954 bodies. So by the time the race began, the Mercedes team were fielding Fangio in a new long-chassis streamlined car with inboard brakes, Moss in a similar one with bodywork from the previous year, slightly higher and marginally inferior in shape, Kling in a new unstreamlined car with inboard brakes, and Taruffi as a guest in a medium-length car with the brakes outboard."

However, this just throws up another mystery or eight: if Sheldon is to be believed, Fangio was in W196-2, one of the 1954 streamliners, Moss was in W196-9 (a car never raced before), Kling was in W196-6 (a 1954 car) and Taruffi in W196-15 (another new car). Sheldon gives T-cars as W196-10 (Kling), W196-12 (Moss), W196-13 (Fangio) and W196-14 (Taruffi).
Presumably the truth lies in there somewhere, but if Sheldon's chassis numbers are correct, then Setright's car allocations are all wrong or if Setright's allocations are right, then Sheldon's chassis numbers are all wrong! Confused? I certainly am!!

Nevertheless, whatever the truth behind this, it proves two things:
1 Mercedes organization was superb.
2 Uhlenhaut was, as occasionally stated, a bloody good driver if he could get a W196 round the Ring only 13 seconds slower than Fangio and 11 seconds slower than Moss. There was no German GP in 1955, but Uhlenhaut's time would have got him second place on the grid in 1954 and 14th in 1957 (practice in 1956 was wet, so no comparison).