Just out of curiosity I started looking into miles/kWh for Teslas, which led to a chart on energy costs of a Tesla vs. some representative ICE car they had chosen.
Ultimately, it would take the energy savings of the first 100,000 miles to pay for the installation of the home charging station.
In the industries that I worked with, the ROI for fast tracked capital funding generally needed to be less than 3 years or so. If a prospective capital expenditure didn't fall into the corp’s fast track criteria, it was tossed into a cage fight with all the rest of the projects to duke it out for funding.
Another class of capital expenditure is a yes/no type such that if I don't spend this $$$, I have to shut down the whole unit. Is this worth decreasing capacity or leaving the business line completely? You usually see this for environmental or obsolete plant related investments.