Τhere is the option for Less Fuel in Route Preference Menu in SP.
Enter your data (estimated fuel milage, fuel prices etc) in Vechicle Profile.
Normally SP creates 3 Routes if possible (time, distance, traffic) and sometimes a forth one (dark blue) which is Less Fuel by itself.
If only 3 or 2 are created, check to see which one has the fuel pump highligted, this is also the Less Fuel Route.
There is no ecoRouteHD for SP, so the Fuel Economy and ecoChallenge values depend on the Gps sensor and the way you drive (hard or smooth braking, hard or smooth acceleration, speed changes and american style speed limits).