Latest data from the DfT shows that in 2015, that the number of untaxed vehicles has more than doubled from 210,000 in 2013 to 560,000 and is now at its highest level for eight years.

The DfT said that this could cost about £80m in lost VED revenue over the course of a year – up from £35m in 2013 – but added that some of this potentially lost revenue will have been recovered through DVLA enforcement activity or by vehicle keepers paying arrears of duty later.

In response RAC chief engineer David Bizley said: “These are very worrying and disappointing statistics indeed. Sadly, the concerns we raised about the number of car tax evaders going up at the time the tax disc was confined to history have become a reality.

“Prior to the new system going live last October the RAC made the point that enforcement would principally be carried out by automatic number plate recognition cameras as is the case with motor insurance where the exact number of evaders is not fully known, although the figure is thought to be over one million.

“We really cannot afford for this to increase again for the sake of both road safety and the country’s finances. Hopefully, much of the increase in evasion is due to the system being new and these figures will reduce as motorists become more familiar with how it works.

“The RAC believes it is vital that this survey is repeated in 12 months’ time – if not sooner – rather than in the normal two-year period so we can establish once and for all whether the increase is simply a temporary result of the new system. If, however, evasion continues to increase, then action will have to be taken swiftly.”

In response, Oliver Morley, DVLA chief executive, said: “Almost 99% of all vehicles on the road are correctly taxed: that’s around £6bn in vehicle tax passed to the Treasury every year. We write to every registered vehicle keeper in the UK to remind them when their tax is due and we have introduced a range of measures to make vehicle tax easy to pay. At the same time we are taking action against those who are determined to break the law.”

A DVLA spokesperson added: "We always recognised the potential for the number of untaxed vehicles to temporarily increase as we moved away from a paper tax disc which had been in place for over 90 years. The fact is it’s easier than ever before for people to tax their vehicles. More than 75% of motorists tax online or over the phone – which includes 11 million switching to paying by Direct Debit since we got rid of the tax disc."

They added: "The report was compiled in the summer, and throughout the year we’ve carefully monitoring how the public have reacted to the vehicle tax changes and we’ve taken a number of steps to make sure motorists understand them. These include writing to every registered vehicle keeper in the UK to remind them when their vehicle tax is due and that the vehicle tax rules have changed. The report also recognises that we will already have recovered a significant amount off the potential lost revenue since the report was compiled by taking action against those who haven’t taxed.

"We quickly identified after the changes that some motorists buying used vehicles were not taxing them immediately, possibly because there was still a tax disc in the windscreen. As a result we have been writing to motorists as soon as they buy a used vehicle to remind them that they must tax the vehicle before they use it. If the vehicle still isn’t taxed, we send another reminder so there is no excuse for them not to tax their vehicle."