I watched the movie Monsieur Ibrahim, set in the early 1960s, and at one point a car dealer is describing a car as so much horsepower, this many cylinders, and “tax category 7”. I’d never heard this- I don’t know if it’s exclusively French or a European thing or if it’s still done at all. Does anybody know what he was referring to?
Some reference to the amount of sales tax payable? Perhaps there were different tax rates depending on the type of car.
Various taxes are fixed at a number of different rates, depending on the vehicle. The British road tax varies according to engine capacity, in a half-hearted attempt to encourage us to choose more economical cars (if you can afford the extra fuel you’re burning, £10 a month extra on the tax won’t put you off your prized ego-mobile).
Exactly what is being referred to in the OP isn’t something I can answer, but I’m sure it’ll be along these lines.