Originally Posted by NotAbel
Something that is obvious when you think about it, but most people don't: map projections are isomorphic views from above, so the distance along a road on a map is only directly correlated to the actual odometer distance if the road is perfectly flat. In hilly terain (the Bay area comes to mind), the distance you travel on the map and the distance you actually roll can be quite different.
Just something to bear in mind.
Agreed.
I discovered this with my Garmin GPS the other week. I usually set my GPS with a way-point to get me to one direction. The GPS will tell me that it's ten miles to get to that way point. If it were a straight line with no hills, that would be the case. It amazes me how it often takes 12 - 15 miles to arrive at my detination!