My question would be if I don’t keep detailed mileage logs (who does?) then can other methods be acceptable, like a Google map printout of the route taken? Or do actually odometer reading need to be in evidence?
If you are worried about audit, you should keep some record. Even if it is “15 miles to see Dr. Smith” on these dates: [list dates]. I think a google map would work. But the key would be the dates, destinations, and individual mileage per trip (not odometer readings).