On Sunday 29th July 2018, 9am - 9pm the town puts on a '60s festival and bans all modern cars from the town, only classic cars are permitted.
More information here: https://retrofestivalcotedopale.com/presentationgb/A city emptied of its modern car to accommodate vintage vehicles. More than 150 volunteers in periode costumes. A 1960’s campsite re-enacted in a park with pond, concerts, exhibitions, vintage market, street performances, véhicles and period decor to dive you in 1960, that’s the Rétro Festival de la Côte d’Opale.
I haven't found the cutoff date for vehicles yet on their website but could be a fun event if anyone fancies a day out in France and dressing up at the same time!