The Motor Insurers' Bureau (MIB) and the Driver and Vehicle Licensing Agency (DVLA) teamed up to launch the scheme.
The bodies set it up some seven years ago, with the five millionth letter sent out to a motorist last month.
The way it works is simple - and bound to spark panic among some drivers.
MIB data showing the car insurance policies of millions is cross-checked with DVLA vehicle records.
The aim of the scheme is simple: to catch drivers without insurance.
If you are caught without insurance on your vehicle, you could receive a fixed penalty notice, a fine of £1,000 or even have your car crushed, the MIB says.
Legislation that allows the MIB and DVLA to take action against owners of vehicles that are uninsured – and not declared to be off the road – was introduced in 2011.
The scheme sees data from the Motor Insurance Database record of UK motor insurance policies cross-checked with DVLA vehicle records to identify drivers that appear to have no insurance.
This system means thousands of insurance advisory letters can now be sent out to owners of uninsured cars, meaning they no longer need to be caught on the road.
The letters warn owners to either insure their vehicle, make a SORN (statutory off road notification) to the DVLA, or face fixed penalty notices, fines and court prosecution.
Neil Drane, head of enforcement at MIB, said that with the scheme in place there is nowhere to hide.
He said: "Data enables us to easily identify vehicles that appear without insurance. By using automation alongside ongoing police efforts, we've helped to halve the number of uninsured drivers on UK roads over the past 10 years."
The MIB is a not-for-profit body that helps innocent motorists if they are involved in hit-and-run accidents or collisions with uninsured drivers.
Ultimately in these situations, the bill is paid through the insurance premiums of all law-abiding, fully-insured motorists.
Source: Birmingham Live