So 2080 is number of hours per working year (assuming zero annual leave and public holidays) I think you should have just calculated 100000/260 to get miles pe

So 2080 is number of hours per working year (assuming zero annual leave and public holidays) I think you should have just calculated 100000/260 to get miles per day, not 10^6/2080. Your 480.8 miles per day should be 48.1 miles per hour. Still doesn't change the huge amount of driving needed to do 100k miles in a year!