A keyless entry system should make a premium car easier to live with, not easier to steal. Yet relay theft remains a real concern for owners of BMW, Mercedes, Audi, Volkswagen, Porsche and MINI models. To protect keyless cars properly, you need to deal with the weakness criminals exploit: the radio signal between your vehicle and its key.
The good news is that protection does not have to be complicated. A few daily habits can reduce the opportunity for relay theft, while the right aftermarket security can stop a thief even if they gain access to the car. The best approach depends on where you park, the vehicle you own and how long you intend to keep it.
How relay theft works
Most keyless systems look for a nearby key fob. When you touch the door handle or approach the vehicle, the car communicates with the key and verifies that it is authorised. A relay theft attack does not usually involve breaking the key’s encryption or physically taking the key from your home.
Instead, two offenders use relay equipment to extend the key’s signal. One device is held near the vehicle, while another is brought close to the key inside the house, often by a front door, window or letterbox. The equipment relays the communication between car and key, making the vehicle believe its genuine key is nearby.
Once inside, the thieves may be able to start and drive away. On some vehicles, they can also use diagnostic access or electronic methods to programme a replacement key. That is why signal protection is useful, but it should not be your only line of defence.
Start with the key fob at home
Your first defence is to block the key’s signal when it is not in use. Do not leave keyless fobs on a hallway table, near the front door, or beside a window. Moving them further into the property helps, but distance alone is not a guarantee if relay equipment is used.
A properly made Faraday pouch or Faraday box blocks radio signals from the key. It is a simple measure, but it only works when used correctly. Put every active key fob inside it, including spare keys. Close the pouch fully, then test it: stand next to the car with the key still inside and check that the doors do not respond.
Pouches wear out, especially when they are folded, carried in pockets or exposed to heat. Test yours regularly rather than assuming it still blocks the signal. A rigid Faraday box is often the better choice for keys kept at home, while a quality pouch can be practical when travelling or parking away from home.
Some newer keys enter a sleep mode after a period of no movement. This can reduce the relay risk, but it is not universal and it should not replace a signal-blocking solution. Check your vehicle handbook or ask a specialist whether your particular key has a motion sensor and how it behaves.
Protect keyless cars with physical security too
Electronic theft is fast because thieves want to be gone before anyone notices. Physical security adds time, noise and inconvenience. That matters, particularly when a vehicle is parked on a driveway overnight or left on a street near transport links.
A visible steering wheel lock remains worthwhile. It will not prevent a relay attempt, but it makes a stolen vehicle harder to manoeuvre and signals that the owner has considered security. Choose a substantial lock that is fitted correctly, not a lightweight deterrent that can be quickly defeated.
Driveway posts, lockable gates and motion-activated lighting can also change the risk calculation. These measures will not suit every home, and a visible gate is not a substitute for vehicle security, but they can make approach and removal more difficult. If you use CCTV, ensure it covers the vehicle and entry route rather than simply recording a wide, unusable view of the road.
For high-risk vehicles, a layered setup is usually the sensible choice: secure key storage, a physical deterrent, an approved tracker and an independent immobiliser. Each addresses a different stage of theft rather than relying on one product to do everything.
Why an aftermarket immobiliser makes the difference
A professionally installed aftermarket immobiliser can provide protection that keyless entry alone cannot. It prevents the engine from starting until a separate authorisation is given, commonly through a discreet sequence using existing vehicle controls. There is no additional fob for a thief to find and no obvious keypad to attack.
This is particularly effective against relay theft. Even if an offender relays the key signal and gets into the cabin, they cannot simply drive away without completing the correct authorisation sequence. The vehicle can appear normal, while the security layer remains hidden.
The quality of installation matters as much as the device itself. On modern European vehicles, security systems must be integrated carefully with the vehicle’s electronics. Poor wiring, incorrect configuration or a generic installation can create faults, leave visible clues or interfere with normal operation. A specialist should fit and test the system without compromising factory functions.
An immobiliser is not a magic answer to every theft method. If thieves have physical access for a long period, any vehicle can be targeted. However, it significantly raises the time, skill and risk required, which is precisely what opportunistic thieves try to avoid.
Do not overlook diagnostic-port protection
Once criminals are inside a vehicle, the diagnostic port can be an attractive target. Depending on the make, model and theft method, it may be used to access vehicle systems or assist with key programming. This is why a relay attack can be only the first part of a wider theft attempt.
Diagnostic-port protection can restrict unauthorised access, while an immobiliser can stop the engine from running even if a thief attempts electronic manipulation. The exact options vary by vehicle, so this is an area where model-specific advice is better than a one-size-fits-all kit.
Owners should also be cautious about non-specialist coding work. Genuine coding and feature activation can be carried out safely, but modifications made without correct knowledge of the vehicle’s modules can introduce security and reliability issues. Use a provider that understands both the convenience features and the security architecture of the car.
Parking habits that reduce exposure
Where you park affects your risk. A vehicle left on a dark road, near an easy escape route, is more exposed than one parked in a well-lit, overlooked location. That does not mean everyone needs a garage, but it does mean small choices are worth making.
When possible, park close to your property but not in a position that makes the key easy to relay through a wall or front window. Keep key fobs in their Faraday protection regardless. On longer stays, such as airport parking or hotel car parks, use a steering lock and avoid leaving spare keys, vehicle documents or programming-related equipment in the cabin.
Be careful with social posts that show a new vehicle, registration plate, driveway or regular routine. Theft can be opportunistic, but desirable cars are also targeted after being identified. Privacy is another useful layer of security.
Check your existing security before spending money
Before fitting anything, establish what your car already has. Some manufacturers offer settings that disable passive entry, change key behaviour or require a button press before access is granted. These settings can be effective, though they reduce the convenience that made keyless entry attractive in the first place.
There is a trade-off. Disabling passive entry may be enough for an owner who parks in a secure garage and wants a factory-only solution. For a premium vehicle parked on a London street or driveway, especially one known to be targeted, a Faraday solution plus an aftermarket immobiliser is often the stronger option.
Check your insurance requirements too. Some insurers recognise approved trackers or immobilisers for certain vehicle categories, while others may specify particular standards. Keep installation paperwork, certificates and service records, as these can be useful if you ever need to make a claim.
When to get specialist help
If you have noticed repeated attempts to access your vehicle, lost a key, bought a used car with an uncertain key history, or own a model that is regularly targeted, act promptly. Reprogramming keys, removing lost keys from the vehicle memory and installing additional security are all stronger when handled before an incident rather than after one.
Secure Code Performance provides specialist vehicle security, key programming and immobiliser installation for owners who need a practical, vehicle-specific solution. Mobile support is particularly useful when the car cannot be left at a workshop or when security needs attention quickly.
Start with the keys you already own: test your signal-blocking storage tonight, move fobs away from external walls and decide whether your vehicle needs an immobiliser as well as a deterrent. Those few decisions can make your car a far less attractive target.
