I am a 17th Century Man!
A small spiral flip is the ticket, I assure you. I bring it in every Saturday and enter into a spread sheet. That takes five minutes and I also reconcile receipts (if any) to support the mileage.
I just threw a wooden shoe at my screen.
Or these:
https://appadvice.com/appguides/show/Mileage-Tracking-Apps-For-iPhone