My wife was recently in a car accident (thankfully no injuries) which resulted in us using a Nissan Altima for a few days while her car was in the shop. It has a remote key and start button combination that allows you to unlock the doors with a small button on the drivers or passengers side doors and to start the car without removing the key from your pocket. For Day to Day use this is really nice since you don’t have to fiddle with your keys when its raining or cold. I did have some specific questions about what the limits of the technology were so I devised a couple of simple tests.
Here are the questions I was trying to answer.
How close to you have to be to unlock the car?
How close do you have to be to start the car?
What happens when you remove the key after the car is running?
Testing Setup
I placed a tape measure on the ground measuring our ten feet (about 3 meters) from the drivers side door. I placed the key on the ground next to the tape measure so I could get some accurate observations. The setup is pictured below.
How close to you have to be to unlock the car?
I started with the key at 10 feet and moved the key toward the car 1 foot until pressing the button on the drivers side door unlocked the doors. At 3 feet the doors began to unlock consistently so I moved the key back to 3.5 feet. At this distance the doors will unlock about 1 our of 20 times.
How close do you have to be to start the car?
Since the key was already at 3 feet that is where I started attempting to start the car. I continued to move the key 1 foot a time toward the car until I had the key placed under the drivers seat on the ground (I guess this is technically –1 foot since the tape ended at the car door). None of these placement would allow the car to crank. Once the key was physically in the car it cranked just fine.
What happens when you remove the key after the car is running?
This test had a different setup. I cranked the car with the key in my pocket and then handed the key out the window to my wife. I drove to the end of our road and back (about 1/4 mile) and got no warnings or unexpected behavior. However when I returned to our driveway I opened the car door without turning off the motor and got a “No Key” warning on the dash. Apparently the key check is only triggered when the drivers door is opened.
Summary
The whole system seems to be pretty nice and reasonably secure from a proximity perspective. I have not done any research on the technologies used in the system so I cannot comment on their general security. The only oddity I have seen is no apparent way to turn on just the accessories of the car. I am sure there is a way to but its not obvious how.