I'm an over the road truck driver, I drive on average about 3,000 miles a week all over the U.S. I have always noticed on several different and expensive wrist watches being either digital or analog, when I return home, my watch is always about 2 to 3 minutes slower than my home clocks, but if I take a week off and stay home, they stay the same.
If I don't adjust the time weekly, in a month my watch would be way off time.
I really noticed it about 3 years ago when I began running a postal route, my home clocks were in sync with the postal time, and those clocks always remained accurate, my watch on the other hand would always end up about 2-3 minutes behind a week.
I even bought a new watch thinking something was wrong with it. But the problem still continued until I realized what was happening.
I was under the impression that much higher speeds, far in excess of 75-80 mph were required to affect a clock in that manner, but apparently not.