The 101km A19 Artenay-Courtenay was completed this week, four months ahead of schedule.
Linking the A10, A6 and A77, it will complete the outer bypass of the greater Paris region.
It is the country's most eco-friendly road thanks to steps taken to prevent any water running off the motorway without being treated first.
To achieve this, the road has 107 run-off treatment basins as well as animal crossings and lots of trees to suck up that carbon dioxide.
Apart from its environmental credentials, the project is also being praised for its record fast completion.
It took just four years to get it up and running from the signing of the concession contract, which concessionaire Arcour claims shows how effective its operator-designer-builder business model is.