FYI, I managed
7.8 L/100 km / 30.1 MPG (US) for the trip, without trying too hard. Enjoyed the scenery!
Main techniques used: drove smoothly; anticipated traffic lights & traffic speed changes in the towns & cities to minimize braking;
manually short-shifted the CVT; kept my speed below 105 km/h (~65 mph) on the open road (110 km/h max limit); chose some routes with a 90 km/h (~55 mph) limit.
There was a helpful tailwind for part of the trip. Cross winds much of the time, but never direct headwinds.