How smart is your car key?

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Had enough of turning keys and pressing buttons? Fed up with rummaging through your bag to dig out your car key? Welcome Keyless Go, an advanced car key system that simplifies the task of unlocking and starting a car.

‘Keyless entry’ for motor vehicles was introduced more than 20 years ago and permits or deny’s access to your car from a single push of a button on the vehicles ‘remote locking key fob’. This remote keyless entry – RKE – removes the need to manually turn a car key in a door lock.

Passive Keyless Entry (PKE) takes driver comfort one step further and lets you lock and unlock your vehicle, and start the engine, without even having to take the car key out of your pocket or handbag.  This advanced driver convenience system was initially developed by Siemens in the mid 1990s and was offered to Mercedes-Benz who gave it the title “Keyless Go”.

These keyless systems are also commonly referred to as Smart Keys or Passive Keyless Entry (PKE) systems and are now frequently used by many other luxury car manufacturers, each giving the system their own name.

How do passive keyless entry systems work?

The driver can either hold the smart key or simply store it securely in their pocket or bag. On approaching the vehicle, the driver is identified by a paired radio transponder chip inside the car key. The doors can then be unlocked and opened by simply pulling the handles.

When leaving the vehicle, the door is either locked by touching a button on the door handle or simply walking out of range. The added luxury continues inside the vehicle, as the engine can be started by simply pushing a button on the dashboard. Again, this is all performed without removing or touching the car key.

How secure are passive keyless entry systems?

Mercedes-Benz car key (2013, The Car Expert)A vehicle operating with PKE will be fitted with several antennae around the bodywork that detect the key signal. Should the antennae fail to function, there is a back-up mechanical key blade concealed in the car key.

The key blade can be manually turned in a door lock that will usually be hidden under a plastic cap for enhanced cosmetic appearance.

Different vehicle manufacturers have developed the Passive Keyless Entry system to work uniquely with their vehicles, and some provide as many as ten built-in antennae.

An independent review of PKE systems examined how secure the systems really are by putting three vehicles under test. The Jaguar XK with four built in antennas, Nissan Pathfinder with just three receivers and a BMW 530xi with an impressive ten total antennas were scrutinised.

The test arranged for all three vehicles to visit a petrol station and have the driver fill-up the car whilst the key was left on top of the boot. An actor then attempted to open a door and steal the car, with the driver just three feet away.

The BMW system was the most secure and only allowed the door to be opened that was nearest to the key, which was the boot. The Jag performed similarly again allowing just the door nearest the key to be opened. The Nissan system with the fewest antenna proved to be the most insecure permitting all doors to be opened, although the vehicle could not be started.

In 2005, Thatcham introduced a standard for keyless entry systems requiring the key to be inoperable at a distance of more than 10cm from the vehicle. In another independent test, Nissan came out on top with the Nissan Micra Intelligent key system.

Rather surprisingly, certain BMW and Mercedes models actually failed the test, meaning it was possible for the car to be driven off while the owner was close by.

Added car key luxury

Some vehicle manufacturers have further developed PKE keys to store user comfort preferences. When a key is within recognisable distance, the vehicle will adjust preset seat and mirror positions, as well as climate control and radio settings. This is a fantastic function if you like your seat laid back and the radio loud, but your partner prefers an upright seat with the relaxing tones of classical FM.

Some cars even allow speed restrictions to be set when used with a specific key.  This gives parents added control over how fast their children are able to drive their car.


Passive keyless entry systems focus on the ‘convenience factor’ and provide added comfort and a touch of luxury for car owners. With the ability to unlock doors and start the engine by simply pushing a button, the old style car key seems slightly archaic in comparison. But I have to question, exactly how difficult is it to turn a key or push a button on a key fob?

Are we really becoming that lazy and strapped for time that even a single push of a remote fob button is a chore? With there no longer being a requirement to remove the car key from your pocket, I feel the chances of losing or having the key stolen are much greater since there is an overall reduced awareness of the key – just sling it in your bag and forget about it, and only realise it’s been stolen three hours later.

Since the smart keys are not required to be turned in the ignition, I suspect there may be the odd moment when the car owner forgets there is actually a necessity to have the key on their possession and attempt to open the doors while the key is still resting on their kitchen table.

Despite my criticisms and the aforementioned security issues raised from the investigations, the National Insurance Crime Bureau has credited smart keys for the 7% reduction in car theft since 2009.

Quick round-up of a keyless entry system

How do you open the vehicle’s doors?
By simply walking up to the door and pulling the handle

How do you lock the vehicle?
Either walk out of range or tap a button on the door handle

How do you start the car?
By either pushing a button on the dash panel or turning the smart key in the dash slot.

When were PKE keys first introduced?
In 1998, by Siemens for Mercedes-Benz.

Which manufactures use PKE car keys and what are they called?
Acura – Keyless Access System; Audi – Advanced Key;  BMW – Comfort Access; Cadillac – Adaptive Remote Start & Keyless Access;  Dodge – Keyless Enter-N-Go™; Ford – Intelligent Access with push-button start; General Motors – Passive Entry Passive Start; Honda – Smart Entry System; Hyundai – Proximity Key; Infiniti – Infiniti Intelligent Key with Push Button ignition; Jaguar  – Smart Key System; Jeep – Keyless Enter-N-Go™; KIA – Smart Key System; Lexus – SmartAccess System; Lincoln – Intelligent Access System; Mazda – Advanced Keyless Entry & Start System; Mercedes-Benz – Keyless Go; Mini – Comfort Access Mitsubishi Motors – FastKey; Nissan – Nissan Intelligent Key®; Porsche – Porsche Entry & Drive System; Renault – Hands Free Keycard; Ssang Yong – Smart Key System; Subaru – Keyless Smart Entry With Push-Button Start; Suzuki – SmartPass Keyless entry & starting system; Toyota – Smart Key System; Volkswagen – Keyless Entry & Keyless Start or KESSY; Volvo – Personal Car Communicator “PCC” and Keyless Drive or Keyless Drive.

Aston Martin's Car Key is called an Emotional Control Unit (2013, The Car Expert)

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Mark Migliaccio
Mark Migliaccio
Mark Migliaccio runs a London car key replacement company called The Auto Locksmith, and also writes on the topics of car security and immobiliser technology.

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  1. Does the Passive Key System used in my Lexus CONTINUALLY send out a signal. If yes, how can the small battery last so long. Thanks for your forum.

  2. Hi Stuart,i bought a new keyless car.i dont understant why the door opens when i pull the door even after ive ensured that i have locked with the remote.kindly explain

    • Hi Vikkie. With a keyless car, it senses the key nearby and unlocks when you pull on the handle. If you don’t have the key on you, it will not unlock.

      Don’t worry, it took me a while to unlearn the old habit of locking the car and then pulling on the handle to make sure it was locked!

  3. hi stu when I looked over a Suzuki sx4 the dealer started the car with a key when I bought the car he obtained a fob from Suzuki and all was well. recently I tried to start the car with the key with no success what am I doing wrong ??? thanks

    • Hi Rick. Not sure what the problem is, best bet is to contact the dealer (or any convenient Suzuki dealership) and ask for an explanation.

  4. Parked up my Renault Scenic while away for two months in Oct/Nov and came back to a very flat car battery. Two months might seem like a long time but my old Ford Mondeo never had any difficulty firing up after this length of time. Both are keyless start but the Renault also has a keyless entry system. Presumably there must be some drain on the battery if the car is idle, waiting for a key to come within range. Any idea what the standby current might be?

    • Hi Martyn. I don’t know what the standby current would be, but you are right in that a car with a keyless entry system is effectively always ‘listening’ for the key to come along, therefore it will be using some power to do so.

  5. My husband I share a Jaguar XF which we both love but there have been a few occasions where one of us needs to drop the other off somewhere and we have had issues because of PKE. They first time it happened my husband drove and jumped out when we reached his destination. It wasn't until I was 45 minutes away and had turned off the car that I realised that my husband had the key!

  6. Comment:
    How safe is my car with keyless entry system? if a thief breaks my car window and gets in the car, can't he start the engine and drive away?

    • Hi Yotam. The car will check for the key, which has to be very close by (usually less than 1m), so if the key is not present, the car won't start.

  7. Can anybody please tell me if there is an aftermarket proximity unit that would suite a 2011 Toyota Yaris Thank you Bob

  8. Apparently it’s now become easy for car thieves to just open your car and start it, then drive of, using some sort of scanner/electronics to hack the security system, a computer can also be plugged into the cars systems which enables would be thieves to turn off any alarm system. Currently some insurance companies are refusing to insure some of the more expensive vehicle because of how easy it has become to steal them. Are there any modifications to nullify this method of theft?

    • Hi Anthony. Have a read of this article about cars being stolen without the car keys, using the exact method you describe.

      I have seen several new Range Rover drivers using old-fashioned steering wheel locks in a desperate attempt to stop their high-priced Chelsea Tractors from being nicked…

  9. We started the new Mercedes and I had the wife walk away with the key. It apparently doesn’t care that the key ‘left’. It still ran. The hypothetical is if the wife left her purse on top of the car (which she has done) with key in purse, and drove MILES away. Then what?

    Conveniences have their drawbacks. I still drive a 2001 Dodge diesel with manual windows.

  10. The owner’s manual advises never leaving the key inside the vehicle. Can I leave the spare inside? Will it drain the battery? I think if a key is inside, you still must have a key on your person to “unlock” and “lock” the vehicle from the outside. I live in a rural area and like the assurance of knowing I can walk out of the house and start the car–even if I “forget” my key. (Theft would not be an issue at our home)

    • It depends on the vehicle. Some cars with ‘smart keys’ will not lock if the key is still inside the car or boot. It’s also a major security risk, and many insurance companies will not cover you if you leave the keys unattended inside the vehicle.

What are your thoughts? Let us know below.