I just heard him talking on an interview tonight and he said he once ran from Santa Monica to Denver, covering 40 miles a day for 4 months straight, 4800 miles. That'd be a rather roundabout route though, maybe he meant 40 days or 1600 miles. Either way, dude is obviously as serious a runner as anyone so I definitely believe his mileage total.
But before tossing out the big mileage stories to give the interviewer what she wanted, he initially answered her "how far do you run" question by saying he runs around 30 minutes a day, enough time for him to do intervals to stay in shape for his competitions at 800 and 1500 meters. So he's not just a mileage hound.