As far as the German vehicle manufacturers were concerned, the 1930s were the 'Roaring twenties'. As of 1933, the sanctions, e.g., the motor-tax, was lifted by the National Socialist government. The development lag, compared with the USA, had caught up a little. Only forty years after the second world war, would Germany again have as many twelve cylinders as at that time, even though they could only be afforded by the absolute upper-class.
1932 - Unbelievably reasonable V8-engine from Ford
Illustrious names like Horch, Stoewer, Maybach (see picture) and Daimler-Benz dominated this class, whereby the last mentioned company did not necessarily represent the top of the class. Besides, one also had consider the most famous names from England, France and of course, the USA. The up and coming Audi and BMW followed at some distance, at that time their significance in the field of vehicle- and engine manufacture, can not be compared with what it is today.
Odd developments arose in the USA, in the research labs. e.g., at GM, where one seriously brought the air-cooled, copper jacketed cylinders almost to the point of mass production. The Americans are actually, well known for their determination. In Germany, the desire to use air-cooling had other reasons. From the beginning of the 1920s, there was a movement here towards lower wind resistance by installing the engine in the rear. A striking-, and long-lasting example is the Porsche, this principle was carried over for construction of the VW-Beetle in the mid-1930s.
The utility vehicle did not realy take off. It was, by no means, widely equipped with the Diesel engine and was actually, responsible for the distribution of goods which were transported by the railways. This tradition would be maintained for a long time in Germany, also after the second world war. Indeed, the road-construction had also not yet caught up. The building of the autobahns started a long time before Adolf Hitler appeared on the scene, they were however, not very well distributed across the country.
At that time, in contrast to today, the finished autobahns resembled roads in a ghost town. It's no wonder that there were suspicions that they were only built for military reasons. Alone buses transported groups of people who were either politically motivated or because of their their work and were still a long way away from owning their own cars. Indeed, also here the Diesel was not strongly represented because the supply of this fuel was only ensured in and around the town itself.
By the way, it appeared that the million-fold 'autombile-country', the USA, wasn't doing much better either. Their giant, -building of highways program- started relatively late. Even the famous Route-66 was only completely tarred in 1938. At that time, utility engines could only be driven at full speed for a limited time. Among the smaller vehicles, the first one to be tested at almost full power, was the VW-Beetle. This fact was still advertised by VW later.