2012 Porsche 911 - Hot Weather Testing in South Africa

The original

VW beetle diesel prototype

In the early 50´s, (1950-1952) Porsche worked on 2 and 4 cylinder diesel boxer engines, due to the low costs on diesel fuel. The development of a diesel boxer was an order from VW to Porsche. 
Basic was the 1.3l Porsche three compartment engine case. The engine had 1.3l and 25hp at 3100rpm. Maximum rpm was 3300. 
The engine ran pretty stinky, was slow, extremely loud and shook the car like an earthquake. 
VW-Boss Heinrich Nordhoff canceld the project. 
Unfortunately, all documents about the diesel-project got lost over the years. This Beetle on the photos is the only prototype and you find it in the Porsche museum. 

1949 Volkswagen Kastenwagen T1 Prototype

"The People's Car" Part 1

Starting in 1931, Ferdinand Porsche and Zündapp developed the Porsche Type 12, or "Auto für Jedermann" (car for everybody). Porsche already preferred the flat-4 cylinder engine, and selected a swing axle rear suspension (invented by Edmund Rumpler), while Zündapp used a water-cooled 5-cylinder radial engine. In 1932, three prototypes were running. All of those cars were lost during the war, the last in a bombing raid in Stuttgart in 1945.The Zündapp prototypes were followed by the Porsche Type 32, built in 1933 by NSU Motorenwerke AG, another motorcycle company.In 1933, Adolf HitlerFerdinand Porsche to develop a Volkswagen (literally, "people's car" in German). The epithet Volks- literally, "people's-" was also applied to other Nazi sponsored consumer goods such as Volksradio. Hitler required a basic vehicle capable of transporting two adults and three children at 100 km/h (62 mph). The "People's Car" would be available to citizens of the Third Reich through a savings scheme, or Sparkarte (savings booklet), at 990 Reichsmark, about the price of a small motorcycle (an average income being around 32RM a week). gave the order to Erwin Komenda, Porsche's chief designer, was responsible for the design and style of the car. But production only became worthwhile when finance was backed by the Third Reich. War started before large-scale production of the Volkswagen started, and manufacturing shifted to producing military vehicles. Production of civilian VW automobiles did not start until post-war occupation.