Today the 250 workers building the Citroën C6 at Peugeot-Citroën’s Rennes factory will down tools for good. Production of the big saloon will end, some seven years after it was launched.

By any measure, the C6 was a sales disaster. Total production may have crept across the 20,000 barrier by today, but that is what Citroën was hoping for in a single year. Sales in the UK probably didn’t bust four figures, making the right-hand-drive conversation one of the most expensive engineering exercises in automotive history.

The death of the C6 is a major landmark for the French car industry. Its demise marks the end of the big French luxury car, a market once defined by marques such as Delage, Delahaye and Avions Voisins. Of course, despite so many established pre-WW2 luxury makes collapsing by the early 1950s, Citroën did manage to re-invent the idea of the luxury car with the DS.

Wildly innovative in its styling and engineering, the DS was one of the most successful reinventions in auto history. The DS was replaced by the CX (an edgily modern fastback and giant estate) and the XM. Neither stopped Citroën from sliding out of the, potentially highly profitable, large car market. Indeed, there was a five year gap between the XM dying and the C6 going into production, suggesting that getting the project to add up on the corporate spreadsheet was a difficult job.

And now Citroën joins sister brand Peugeot and Renault (who crashed ingloriously out of the large car market when the oddball Vel Satis was killed off in 2009) in not having a proper flagship model. National pride aside, does it matter?

Financially, it’s a big hole in the accounts because Mercedes, BMW and Audi make significant margins on their large cars. Then again, the German big-three completely dominate the global large and luxury segments, so the French are in good company. More tellingly, the French makers completely ignored the premium SUV boom, missing out on a very lucrative market that might not have been so badge-sensitive during its formative years.

Perhaps it is this determination to do things their own way that has been responsible for the French big three being slowly expelled from the large car market. Worse still, sister cars the Pug 508 and Citroën C5 could yet be merged in with the next-generation Vauxhall/Opel Insignia because falling sales and a shrinking European market for non-premium large cars is making it hard to even break-even.