You wouldn't say it, but yes: they made prototypes and testcars to study the new vehicle. In 1968 VW made 16 prototypes to be tested by the German army. A big mystery about these cars because no-one really knows what happened afterwards with those proto-181. Our best guess is that they were redone in 1970 and went in Bundeswehr service.The picture below shows us the only known survivor of the prototype-serie (left). Easy to spot the difference with the later production type on the right: there is one rib less under the doors and the prototype lacks the embossed support for the VW-emblem on the front panel.If you see a 181 with one rib: you are very lucky... or just watching at a bad repairjob.