Don't know but this should help. Any anyway it will only be an extra few pound
On leaving Calais, take the A16 motorway south past Boulogne.
On leaving Boulogne (south of Calais), follow signs for the A16.
Join A16 in direction of Le Touquet and Abbeville. Continue on the A16 to ABBEVILLE.
At junction 23, follow direction Le Treport/ROUEN/Le Havre to reach the motorway A28, missing out Abbeville town centre.
As a new chunk of motorway (only shown on the most seriously up-to-date maps) has come on-stream, those of you prepared to negotiate Rouen will be able to lop up to an hour off the journey from Calais to the Vendee. I have not yet used this route myself; but you can view the detail of it using http://www.viamichelin.com/ for the following description (here’s a link to the site in English):
To use this new route, take the A28 southwest from Abbeville all the way to ROUEN. Then go round the eastern bypass and look for signs to ALENCON/ LE MANS.
* There is a serious lack of petrol stations on the new section Rouen to Alençon, apparently, so be sure that you have enough to see you through.
* See bottom of page for a hotel near Rouen that makes a possible stopping-place for travellers driving from Calais to the Vendee.