I think you can get something similar to this nowadays even from the big insurance companies. I thought I remembered some startups doing micro-transaction insurance policies that started and ended with each new trip -- did some searching and found that Allstate has something similar: https://www.allstate.com/auto-insurance/milewise

You pay a small retainer fee ($1.50/day) and then a per mileage fee. This requires the use of a logging device which also impacts your per-mile rate depending on your driving.

I haven't dug into the nuts and bolts of this, but I wonder how well you are covered when the vehicle is not in motion - parked in garage, on the street, etc. At least in my area parking in public can be a risky option between the hit and runs, catalytic converter theft, break-in, etc.