I like the concept of the leafball as a visual reminder to be efficient, but it seems to do nothing more than monitor aggressive acceleration and braking.
For example. At 60 mph or so a tractor trailer passed and I decided to draft to see what the green leaf ball would. It didn't budge. I can tell you from driving an EV with an ampmeter on board that doing so saves 100 to 150 amps...which is a very big deal. Not saying you should do this...but it just demonstrates that the leaf ball doesn't really correlate to actual energy usage in many ways.
Want to know whether rolling down the windows or running the AC would be more efficient...no way to know with current system
The volt obviously knows exactly how much energy it is using, why not make that info available to the driver so he can decide which actions and conveniences are worth the energy expended? This is something that could be implemented immediately with a software update.