The important paragraph that most people probably care about: Soon, Google Maps will default to the route with the lowest carbon footprint when it has approximately the same ETA as the fastest route. In cases where the eco-friendly route could significantly increase your ETA, we’ll let you compare the relative CO2 impact between routes so you can choose. Always want the fastest route? That’s OK too — simply adjust yo…
I'd be curious to know if that maps onto the lowest energy use in an electric car. Because I've been wanting that feature for long-distance EV trips for a while now.
It just does not let you specifically route for energy use. You can choose to route for money (tolls), charging stops or traffic if you enabled online routing.
When you plan a trip, it has a page that shows a graph with predicted vs actual energy use. If you keep the "actual" line above the "predicted" line, you will make it, otherwise you may not.
Thing is, the predicted line clearly shows the route ahead with the slope of the curve mapping against climbs and descents.
If you read the manual it says:
"The calculation is an estimate based on driving style (predicted speed, etc.) and environmental factors (elevation changes, temperature, etc.)"