Earlier quoted context omitted.
> The "2CV" in the car name was kind of a tax fraud, though. It was not, the taxable horsepower and the “actual” horsepower are completely different things, as the former is derived from displacement (and / or gear speed at a fixed rpm). There was no fraud because this was how it was expected to work.
From my point of view, making the taxable horsepower a completely different thing from the actual horsepower is a fraud. Maybe you mean that the fraud was perpetrated by the tax office and not Citroen?
At the time nobody cared about the real horsepower anyway. Until the late 80's the only benchmark that people view in term of car performance capability was the top speed and at a lesser level the 0 to 100kph numbers. The first speed limits had been introduced only in 1974 and at first been presented as temporary measures.