Common sense would tell you that it is not wise to leave the kids alone in the vehicle, even if it is for a minute or two.
I don't even leave my kids alone in the car for a minute or two for several reason. If I'm stopping at a gas station for an "in and out" thing, I take them with me. If I'm stopping by a friend's house to drop off some stuffs, I take them with me.
Even if I were to trust my kids to be alone in the car for a minute or two, I couldn't bring myself to do that because my kids are at the age where they are curious, mischievous and they could try to unlock the door, mess around in the car.