Just for Grins...
in the US... around the era of Model A's in the 30's there were Roadsters, Convertibles, Cabriolets, Coupes and Sedans. Hardtops (or pillar-less) were generally not invented until the '50's if I recall.
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Roadster was generally an auto with ONLY a windshield (windscreen) and absolutely no side windows or tops.
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Convertible was usually a rag-top that folded and either had no side windows at all or some snap on types that were, and still are, found on Jeeps today. Another name from Europe were "Drop-heads" and I imagine there were more...
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Cabriolet was usually a modified Coupe of sorts that had solid window frames on the side doors and a fixed windshield, but had a canvas covered top and rear portion that either folded, came off, or was actually AFFIXED to the solid top... ala fake convertibles you see today, or vinyl tops you saw in the '60's to '80's. They French had several Cabriolets with their Citroen's and so did FIAT with their original, as well as the new 500's.
Many of the earlier FIATs were so called Cabriolet's but were actually Convertibles... Confusing, huh... but that was the term they used and proper for that year when describing it to others. FIAT 1200's and 1500's standard layout Sports Cars were called Cabriolets back then...
Coupes, Opera Coupes, 2 and 4 Door Hardtops, 2 and 4 Door Sedans, 2 and 4 Door Station Wagons, Tradesmans, Nomads, SUV's, Crossovers and on and on are many times confused or misunderstood by the speaker... and I guess not so important for this discussion. Then there are Sports Cars, Muscle Cars, and Sport Coupes... We could spend hours at this... HA!
I think I heard a (VW?) commercial lately that described their car as a HARTOP... and VW doesn't make a pillar-less car... I useta think hardtops were sedans or coupes because the pillars would make the tops HARDER to crush in a rollover... I guess the original intent for the name was that the TOPS were so HARD, they didn't need pillars!
Which reminds me... back in the 30's, most COUPES and SEDANS may have had what looked like a solid roof, but the center sections were usually framed and covered in a shellacked material of sorts. It was just too difficult to stamp big sections in those days.
OK... I'm done... Over and out for now...