Al
My Magnum BMKs provide all the information I need, but not necessarily all some may want. I'm with FF, in and out measurement combined with volts is a pretty good indicator.
If one wants to balance battery capacity and draw down rates wants and needs, a trip to a Tesla dealer will show you what can be done, but at a price. A simpler and perfectly workable display comes with the Prius. Simpler yet is the Ford Fusion's. The auto circuitry is interesting to study, especially when giving precise instructions to the IC engine start and shut down modules.
Good subject, it will be interesting to see how many dollars you are willing to spend to achieve your goals. I stopped at around $800.