The Leaf shows Miles/kWh instantaneously and along with the trip computer resets. There is even a separate reset on the center console you can do to track history at whatever intervals you choose.
Very useful and a glaring oversight to me who is used to monitoring that as my primary "mileage" indicator while driving the Leaf.
I hardly plan to use gas on the Volt so putting everything in terms of MPG is nonsense.
2012 Blue Topaz Metallic Volt delivered 7/31/12 charged with Ecotality Project Blink EVSE
2012 White Diamond Tricoat Volt delivered 6/29/12 charge with Ecotality Project Blink EVSE
2012 Cayenne Red Leaf delivered 3/29/12 charge with eVgo/Aerovironment EVSE
6kW Solar array