The E40 motorway goes all the way from Calais to the Kazakstan/China border. Is there a longer road than this?

I think the Trans Canada Highway is longer than that. It runs from St. Johns Newfoundland to Victoria BC, with breaks for the water crossings. Even if you only count the continental part from the Maritimes to Vancouver, it's longer. The Pan American Highway from Dead Horse Alaska to Ushuaia Argentina is much longer, but it has a 500 km. break for the Darien Gap, a section of unroaded jungle in Panama. Of course, it depends how you define a continuous road. You can drive all the way from the northwest of Brittany to the Burmese border, or from Tangier or Alexandria to Cape Town, or from Key West to Dead Horse. But the E40 would be one of the longest named roads.