An app for indoor tracks that allow me to set a fixed distance per lap.
The current Garmin app uses stride lengths (I think) to determine a distance. The Garmin result is usually very different from the actual distance ran. For example, my track is 9 laps per mile (in the center lane). I did 30 laps (3.33 miles). Garmin said I ran 3.01. Not a huge split, but it only gets worse the further I go.