Trip Odometers

It would be great if you could add a simple custom trip odometers feature that allows you to set an arbitrary start mileage and have TeslaFi display trip odometer stats (miles, kWh, time, etc.)

My personal use case would be entering the mileage from when my tires were last changed/rotated to keep track of tire miles. In other words, make it retroactive so I could set the start the odometer at a previous mileage and see stats since that point in time. 

In addition, maybe have a countdown feature that you can set so that when you hit X,XXX miles it will give you a notification. Basically a maintenance reminder. 

Thanks for the great product!