I don't think there's a hard-and-fast rule for this. I'd do it on a case-by-case basis; a few things that come to mind:
If my older daughter were old enough to drive, I'd let her drive her sister to the mall or to a school function.
I would probably say "yes" to an afternoon trip (daylight and light traffic). I would not allow my daughters to drive after dark or in rush-hour traffic with a new driver.
I would be more inclined to allow them to drive with JUST the driver instead of a group -- the group is more likely to get rowdy and distract the driver.
I would probably let them go to the mall (2 miles) with a young driver, but I would not allow them to go into the big city (20 miles).
I would proabably let them ride with someone I knew well and considered responsible in other areas of life, but I'd be less likely to let them ride with someone I don't know -- or someone who has appeared to be irresponsible in other ways.
I would not let them drive with a teen whom I know to have had tickets (because that means they're driving irresponsibly and have been caught at least once).
I would not allow them to go on "car dates" until at least 16, but that's not really about the driving.