The D roads are designated roads of a certain class in France, not much different than numbered highways designated US; some are quite pleasant in rural areas and others are not. D roads don't get a better or worse group of motorists than other roads in France.
BTW I didn't find French drivers all that wonderful, and felt that German drivers' conduct towards cyclists, as well as German roads, and off road cycling routes typically superior to those in France. The percentage of the population in eachNation that uses a bicycle for transportation as well as recreation is partially a reflection of this.
D roads are departmental roads in France and completely unlike US designated highways. No comparison.
I lived in Germany too.
Having toured many thousands if not tens of thousands of miles in France, cycling rural D roads is heaven for me. Just my opinion.
Falls City, OR
1993 Rocky Mountain Fusion
2012 Fargo 2
I understand that there aren't many cars in Cuba. I've never been there and I understand there is the little matter of personal freedom.