It's easy to find sites claiming that Colonel Sanders drove at least 250,000 miles per year.
TV Tropes makes this claim:
Even in his advanced age, he drove himself upwards of 250,000 miles a year in his own car visiting individual restaurants and promoting the chain.
The University of Houston goes so far as to claim that he maintained this pace even up until 90 (though this source does not, strictly speaking, claim that he drove):
At the age of 90, the Colonel was stricken with leukemia. Until his death in 1980, he traveled 250,000 miles a year, visiting the KFC empire that he had founded.
Even Wikipedia makes the same claim, albeit with a bit more nuance:
Sanders died in 1980 from pneumonia at the age of 90, having continued to travel 200,000–250,000 miles a year up to this time, largely by car, promoting his product.
My skepticism here comes from the fact that at a reasonable average pace of 60 miles per hour (the legal speed limit was between 55 and 65 miles per hour for most of the later years of his life), this would mean, on average, driving more than 11 hours per day, 365 days per year, a very punishing schedule.
Did Colonel Sanders travel 250,000 miles per year? If so, did he drive 250,000 miles each year, and particularly, did he drive himself?