The other thing to consider, especially in non-rush hour, is road design. Commonly used routes are likely to be BUILT for all that traffic. They are going to be simpler, straighter and more convenient for impromptu stops (gas, snacks, chores-en-route). Would love something like this suggestion + tolerance thresholds for switching to a faster route. Also perhaps a voice driven selection when a faster route has been determined. "Good news we have found a route which will reduce your trip by 10 minutes. There are tolls and it's 5 miles longer. Do you wish to take it?"
The other thing to consider, especially in non-rush hour, is road design. Commonly used routes are likely to be BUILT for all that traffic. They are going to be simpler, straighter and more convenient for impromptu stops (gas, snacks, chores-en-route). Would love something like this suggestion + tolerance thresholds for switching to a faster route. Also perhaps a voice driven selection when a faster route has been determined. "Good news we have found a route which will reduce your trip by 10 minutes. There are tolls and it's 5 miles longer. Do you wish to take it?"