Track and Field Blogs - Austin Waldrop

I did my mile repeats today and I tripple checked my route on all the sites including usa track and field for a total of 6 sites and I read somewhere that if a device, which I forgot , in the car is off then the odometer is off and then I checked it in a car. The car got a shorter distance. Then again when i run, I run on the edge of the road. Why do my car and these map sites get different stuff. I hate to ruin a great interval session but the .1 a difference in the two measurements can make a great workout a terrible one. Any ideas on this. It just gets on my nerves that I am running very very hard and that I might not be as fit as I would like. Thanks for any comments.