The use of Proper needs to be defined in this usage for this question to make sense.
French cars are smaller/slower(excluding bugattis).
French is a proper adjective. France is a proper noun.
Quite a few steam cars. The Benz Patent Moterwagen (the first proper car) The Royal Enfield (a quad bike) The de Dion-Bouton (French and complicated and one of the first cars that sold in grat numbers)
The three French makes of cars are Renault, Peugeot, Citroën.
The Peugeot, Citroen and Renault are all popular French cars in Australia.
No Australian cars are French. Two makes of French car driven in Australia are Peugeot and Renault, but there are not very common.
They seem just fine for the French. Most of French-made cars (often built in Eastern europe) are fuel-efficient and not as pricey as German cars for comparable prestations.
French people drive hubbies cars or other quaint cars that we use in modern life.
Peugeot and Citroën are two well-known makes of french cars
The word French is a proper noun, a word for the people of France. Proper nouns are always capitalized.The word French is also a proper adjective, for example, French food.
All cars need a thermostat for proper operation and longevity.
The noun 'cars' is a common noun, the plural form of the singular noun 'car'; a general word for a vehicle.A proper noun is the name of a specific person, place, or thing. Examples of proper nouns for the plural, common noun 'cars' are Fords, Ferraris, or the 2006 animated movie "Cars".