strange calculation in navigation

In my Prius+ I have the original Toyota navigation. In my last trip from France home (Netherlands) it gave some strange calculation in the
available choices: Fast route: 863 km, 17:11 arrival time Ecologic route: 861 km, 17:09 arrival time
How can the ecologic route be faster then the fast route?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.