Overnight key store theft is a major problem for UK car dealerships. Thieves use relay attack devices to capture and amplify key signals. These devices cost as little as £200–300 online. The relay extends the signal through locked doors and unlocks vehicles. Thieves drive them away before staff arrive. A secure key store is your first line of defence.
For dealerships that already operate alarm systems, security fog adds a proven second layer. It fundamentally changes how thieves assess the risk of attacking your site. The evidence is clear: 97% of thefts are avoided with a fogging system AND an alarm, compared with 17% with an alarm only (Density® manufacturer figure).
The Relay Attack Threat to Dealership Key Stores
Relay attacks extend the range of car key signals. A thief stands outside with a receiver device. An accomplice holds a transmitter near your key store. The signal passes between them. The car thinks the key is present.
This threat has grown sharply. Relay attacks now account for approximately 70–85% of all vehicle thefts in England. The German General Automobile Club (ADAC) tested 237 modern keyless vehicles from different manufacturers. They successfully broke into 230 of them. Only 7 vehicles resisted attack. These attackers are organised theft gangs using mass-produced relay devices.
Dealership key stores are attractive targets. They hold many keys in one place. One overnight break-in can mean losing dozens of vehicles, each worth £15,000–£40,000 or more. The financial impact is severe.
Why Alarms Alone Are Not Sufficient
A traditional burglar alarm detects a break-in and sounds a siren. It alerts the monitoring centre and calls patrol. But relay theft is fast. The vehicle is unlocked, started, and driven away in minutes. Patrol arrives too late.
97% of thefts are avoided with a fogging system AND an alarm, compared with 17% with an alarm only. Density® manufacturer figure.
Security fog changes everything. It provides an immediate barrier that stops the theft before it starts. When a relay-based intrusion begins, fog floods the key store instantly. Thieves cannot see. They cannot move through the space. They cannot find keys or vehicles. The attempt fails within seconds.
How Security Fog Works Against Relay Theft
Security fog creates total darkness in the key store. When a thief enters, they see nothing. They cannot find vehicles or keys. They cannot get their bearings. Fog stops the theft attempt.
The fog itself is non-toxic and has been certified by Eurofins. It meets toxicological standards to EN ISO 16000-1:2006, making it safe if staff are briefly exposed during normal business hours. It disperses naturally within 15–20 minutes, allowing your dealership to resume normal operations.
Fog systems meet the standard EN 50131-8:2019. They integrate with all alarm panels, including Ajax. Remote monitoring via ActiveCloud is free, so you can track deployments in real time.
Sizing and Installing a Dealership Fog System
A typical key store occupies 20–40 cubic metres. It might be a staff room, cabinet area, or small office. The Density 900 covers up to 900 m³ and deploys in under 60 seconds. For larger areas, the 1500 Lite covers up to 1,500 m³.
The generator mounts discreetly on a wall or inside a ceiling void. When your alarm system detects an intrusion—motion detected, a door forced open, or a relay signal intercepted—the fog releases automatically. No manual activation is required; the system responds instantly.
Installation integrates with your existing alarm wiring. No separate power circuits are needed if your alarm panel supports relay triggering. Many dealerships install dual fog zones: one in the key store itself, and a second in the main showroom. Both link to the same alarm panel for synchronised deployment.
Integration With Your Existing Security Setup
Security fog works alongside your alarm, never replacing it. The alarm detects the intrusion and triggers the fog release. This layered approach—detection plus fog—creates effective defence in depth. Any burglar now faces instant total darkness and sensory disorientation, making the attack impossible to complete.
Fog systems also integrate with CCTV and VMS platforms via LAN and API. This means you get detection, fog deployment, remote video monitoring, and rapid patrol response. This combination of technologies makes your dealership an unattractive target for relay thieves.
Read more on how security fog protects showroom vehicles and key stores across multiple dealership scenarios and premises sizes.
Real-World Installation and Maintenance
A typical dealership installation begins with a 15–20-minute assessment. We measure your key store volume, check your alarm panel compatibility, and identify the ideal generator position. Most installations complete in a single day with zero disruption to your daily operations.
The fluid canister requires replacement after each fog deployment. In practice, full deployments become rare once word spreads in local theft networks that your dealership is protected. Annual maintenance includes canister checks and sensor testing to ensure the system remains ready for deployment.
What About Overnight Staff and Contractors?
If your dealership maintains overnight staff (night watchmen, valeting teams, contractors), safety is the primary concern. The fog is non-toxic and tested to EN ISO 16000-1:2006. Brief exposure during normal hours is safe. Your deployment protocols should instruct staff to exit the fogged area immediately and wait for the all-clear from your alarm monitoring centre.
Most dealerships disable the fog system during active overnight staffing and re-enable it during closed hours. Your alarm provider can program multiple armed modes to support this operational flexibility without compromising security.
Frequently asked questions
How quickly does the fog deploy?
Fog systems release a full room fill in under 60 seconds. The thief cannot see to locate vehicles or navigate the space safely.
Will the fog damage vehicles or the key store interior?
No. The fog is non-toxic and leaves no residue. It disperses completely within 15–20 minutes, leaving no oily film or corrosion risk on paintwork or electronics.
Can relay thieves disable a fog system before it triggers?
No. The system is hardwired to the alarm panel and deploys automatically on alarm trigger. Thieves cannot jam, disable, or bypass it remotely.
What does a fog system cost to install and maintain?
Installation cost depends on your key store volume and alarm panel type. Contact Density Security Fog for a site survey and quotation tailored to your dealership.
Does the fog work if my dealership already has an alarm system?
Yes. Fog systems integrate with all existing alarm panels. Your alarm detects the intrusion; the fog deploys instantly. If you do not yet have an alarm, install both for the most effective protection.
Taking Action to Protect Your Key Store
Relay theft is now the dominant mode of vehicle theft in the UK, and dealership key stores remain high-priority targets. An alarm alone provides detection only. Fog provides an active, immediate barrier that makes relay theft impossible to execute.
The 97% figure speaks clearly: a combined fog and alarm system is far more effective than an alarm alone. If your dealership currently relies only on alarm systems without a physical fog deterrent, you have a security gap.
Explore security solutions for car dealerships, or browse our full product range to understand which fog system best matches your key store volume and dealership layout. Contact Density Security Fog today for a free, confidential site survey and security assessment. Our team will measure your space, evaluate your current alarm setup, and recommend the most cost-effective fog solution to protect your inventory overnight.
