In 2004 Mercedes marketed its CLS as a 'four-door coupe' and its success has spurred rivals to copy it. But are car makers abusing the true definition of the word 'coupe'?

Is there such a thing as a four-door coupe?

Most dictionaries continue to define the word 'coupe' as "a two-door car with a fixed roof and a sloping back", but more car makers continue to defy the book of English.

Audi has just unveiled the A7 Sportback, which joins the recently released A5 equivalent as yet another luxury four-door 'coupe' - or five-door 'coupe' if you count the liftback hatch door - that continues to blur the lines between a traditional four-door sedan and curvy sports coupe.

I guess we have to blame Mercedes-Benz, which kicked off the modern trend in 2004 with the successful and swoopy, E-Class-based CLS (of which a new-generation version is due soon).

Volkswagen copied it with the Passat CC, while other car makers have jumped on the bandwagon - including Aston Martin (with its beautiful late-comer, the Rapide) and Porsche (with its ugly-but-technically-brilliant Panamera).

Jaguar's new XJ limo also flirts with the styling theme, while BMW is planning a production version of this year's Gran Coupe concept.

There have also been some cars that were launched too prematurely for the segment. Fish-inspired Ford Taurus anyone? And c'mon, admit it - the first time you saw the rear styling of the Mercedes CLS you also mistook it for Ford's unloved AU Falcon.

Do you think these style-focused cars are nothing more than just short-term 'flavours of the month' or do you see the trend continuing? And should car makers be allowed to spin names to their liking by calling a four-door car a coupe?

And which one of the current brigade of slope-backed sedans is your favourite?

Chris Harris