For someone to do that every day for 8 years and still do sales work would be some kind of endurance feat.
Days in a year: ~365 x 8 = 2,920; 1,000,000 / 2,920 = 342.5 miles per day
W/o weekends: ~260 x 8 = 2,080; 1,000,000 / 2,080 = 480.8 miles per day
That's more than 5 hours of driving, every. single. day. Unlikely.
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!