The poll by Motoring.co.uk found that 30% of motorists do not know when their Vehicle Excise Duty is due, meaning that over 13.5 million of the 45.5 million people who hold driving licences in the UK could forget to renew it.

Motorists driving without valid tax could be fined up to £1,000 and face having their vehicle impounded.

The firm said that the findings would seem to imply that the new digital system set up by the DVLA is failing but added that a spokesman from the DVLA said: “The vast majority of people tax their cars on time, with over 42 and a half million drivers taxing their vehicles since 1 October 2014.

“Of these more than 29 million have chosen to tax their vehicles online or by phone. We also still send reminders to motorists when their vehicles are due to be taxed. We send V11 reminders to all motorists except those who have chosen to pay by Direct Debit – they would receive a Direct Debit reminder.”

Terry Hogan, co-founder and director of Motoring.co.uk, said: “This latest poll reveals that the lack of a physical tax disc is a major factor in motorists forgetting to tax their vehicles, meaning large numbers of motorists are failing to renew their car tax, driving illegally and liable to fines.”

The company also highlighted its MyMotoring hub, which allows users to easily log a few car details and then sends out timely reminders when their road tax is due.