Taking your family member's things without their permission is wrong.
Steve, who lives with his mom that has an appointment that day, is planning to shop in town, but his car refuses to start.
Steve wants to go to town.
Steve asks his mom if he can take her car to town.
Steve takes his mom's car without asking and goes on a shopping trip.
Steve's mom drops Steve off in town, then goes to her appointment.
Steve's mom can't get to her appointment, as her car is gone.