Sorry, this is off topic (but whenever I see car talk, I always have a need to chime in). Your truck is off by 20%? Did you get aftermarket wheels/tires for your truck or are they OEM?
To get this back on topic...Yup! I actually use a couple car apps for my car that use GPS. I don't use it for a speedometer because I have a secondary digital as part of the instrument cluster, but the GPS comes in handy when trying to track how off it might be (in the event I've gotten the car re-alligned or new tires, I test it out to make sure it's accurate).
What are the other types of GPS issues you've heard of, aside from the OP's specific problem?
I agree about the locating satellites issue. What's strange to me is that, I've had situations on a couple road trips where we went into a roaming area, while I was using nav...the nav (google Nav) would maybe lose signal for a split second and then pick up as soon as there was a tower.
butie120, one thing I can think of that might be an issue is...do you have your data set to stay on while roaming? That could play a HUGE factor in your GPS being able to pick up a stronger signal. There's no reason not to do that because roaming shouldn't cost any extra on Sprint.