text: Thats easier to imagine than a car-free Champs Elysees. Congestion was down 60% in the capital of France, after five-days of intensifying smog. Diesel fuel was blamed, sinced Franced has. . . a tax policy that favors diesel over gasoline. Diesels make up to 67% of vehicles in france, compared to a 53.3% average of diesel engnes in the rest of Western Europe, according to Reuters.