There's an app called MapMyFitness that records by GPS rather than by body movement. It definitely will record when you're in a car, which I've discovered when I forgot to end its record after a walk. You do have to turn it on any time you want to record, and it takes a bigger toll on your battery power. I'm not sure that it would work in stores like Walmart anyway, where the roof and structure may interfere with GPS. Good for you for "making up" for the lost 0.3 miles!