When you first hear of this, it sounds like a bad idea. A lot can go wrong with allowing a stranger to unlock your car while you're inside. But Amazon not only thinks it's new delivery service Amazon Key is perfectly safe, it's guaranteeing it.

To use Amazon Key you must live in a select number of cities and states. You also must be an Amazon Prime member. You also must have a certain kind of car with OnStar or OnCall. A 2015 or newer Buick, Cadillac, Chevy, GMC or Volvos. When you order something from Amazon, you choose 'in-car delivery'.

You'll get a notification on your phone when the driver is on his or her way, and another notification when your package has been delivered.

Of course there are some things that COULD go wrong. What if the delivery driver steals your car? This is highly unlikely for a car with OnStar or OnCall security, and they are granted access only to unlock and lock the door as well as open it.

What if the delivery driver delivers it to the wrong vehicle? This isn't very possible since the driver will be able to see the model, type and year of the car as well as the license plate.

What if the delivery driver forgets to lock the door? Just as anytime using the OnStar system you can see if and when doors are locked/unlocked and you'll be able to lock them from your device or a computer.

And Amazon is guaranteeing things will go well by offering deliveries a "happiness guarantee" which will cover the item and any damage to your vehicle.

If they can't get into your car to make the delivery, the driver will drop off the item at the business or residence address you register with Amazon.

There are some things that COULD go wrong with Amazon Key deliveries but that can also be said of deliveries to your home doorstep. A survey done last fall showed at least 30% of Americans have had deliveries stolen from outside their home