This is causing me nightmares. The exhaust arrangement suggests a 4-cylinder engine, but the 28/95 had 6 cylinders.
The Mercedes team for the 1922 Targa Florio comprised 7 cars - 2 X 28/95 models, 2 X new 1.5-litre supercharged cars, and 4 of the pre-WW1 1914 Grand Prix cars. These latter cars had 4 cylinders, and I know that Brooklands regular C G Brocklebank had one which was converted by L C Rawlance into a road-going car. HOWEVER - that was in 1923, and this car is bodied in a style which would have been around 1928-1932.
Sorry. Obviously I don't know the answer. These are just observations.
