I found the picture in here
, with the following description:
#32 von Morgen (Bugatti 51139)
#33 Caracciola (Alfa Romeo)
#46 Divo (Bugatti 54210)
#36 Willams (Bugatti 51)"
According to this Wikipedia page
, the race in Berlin, Germany, took place on 22 May 1932. This page also contains the picture below which must have been taken right after the one shown above. In the foreground is the 7.1 litre Mercedes SSKL #41, driven by von Brauchitsch, who won the race in by passing Caracciola's Alfa in the last lap after an almost legendary battle for the lead that lasted more than half the race. The race report here
says "While Caracciola in the nimble Alfa Romeo always gained an advantage in the corners, the bulky Mercedes-Benz made up the lost time on the straights." -- the two straights were 9.5 km (almost 6 miles) long.
This pictures above and below were taken by photographer Georg Pahl, available from the German Federal Image Archive (Bundesarchiv)
. Note the different color of the radiator shroud in the picture below, which shows Caracciola in front of the Alfa (this may be a different car according to the race report here
, which says Caracciola tried a red car and a white car in training, so it's possible the car that entered the race was a hybrid of both cars). Interestingly, the archive has no pictures showing the Alfa after the race started.