Since only purchasing the car 2 weeks ago, it had 3/4 of tank, finally did a fill up of 12.69 gallons, when the gauge read 18 miles to empty. They had not reset the trip previously, so I;m not sure the exactly mileage yet. But the AVG has been increasing slightly. the Avg. on the gauge was around 37mpg when i first got it. Everything was reset when they did all the updates at the dealership.
It's avg. right now 39.4mpg and has been slowly increasing with mixed hiway/city driving. probably 80% hiway/20% city. Next tank will know much better, I know when I filled it up, it came back and said 525 miles to empty on the trip. So, if I figured 525 to empty / 12.69 gallons it took to fill it up, that comes out to approx. 41.4mpg.
Mine has learned my home and work with the EV+ about 1/8-1/4 mile from the destination.