Select show routes, then scroll down to the bottom and pick options, on the options list you can avoid highways or toll roads. I use a mixture of modes to optimize my trips. I do a weekly 60 mile round trip to Needham, MA. I choose avoid highways for the first 20 miles of my trip because it shortens the trip and the roads are very scenic. For the last 10 miles I switch to highway mode unless Maps shows that there is a traffic jam. Switching to highway for the last 10 miles shortens the time significantly. Overall my travel time is almost the same as if I did all highway, but the distance traveled is shorter and the MPGe is much better. Yesterday's trip was 65 miles round trip, I had 5 miles left on my guess-o-meter when I got home.