Post script : I got 53.4 mpg on the way there. Only got 43.9 mpg on the way home. Our dinner location was out in the country at a house at the bottom of a very steep driveway. When we were leaving I engaged the power mode button and then accelerated briskly to get a running start at the hill. In doing so the drive wheels broke loose a bit on the gravel. Later when we got to the freeway I noticed that the cruise would not engage and the EV and ECO symbols would not illuminate on the HSD. When we got home I turned the power off and waited a minute. Then I restarted and the EV symbol was once again illuminated. It would appear that spinning the drive wheels tweaks the car's brain and it must then be re-booted to regain it's composure.
