Growing numbers of motorists are joining a class action lawsuit against VW in England and Wales, putting the spotlight back on the government to take action.
So far, over 36,000 motorists have joined a class action lawsuit against the German car giant and the total is rising at a rate of around 500 drivers a day.
The action wants compensation from VW for selling cars that the lawyers say were not fit for use, as defeat devices were used meaning emissions were far higher than they appeared to be.
While the car firm pleaded guilty to all criminal charges in the US, admitting to conspiracy and obstruction of justice using its scheme to overcome pollution restrictions, and agreed to pay $4.3bn (£3.5bn) in civil and criminal penalties, the UK government hasn't taken VW to court.
Damon Parker, head of litigation at law firm Harcus Sinclair, which launched the action with Slater and Gordon, said the government has said it will support UK consumers taking legal action, but "the more pressure put on VW the better".
In terms of the growing numbers of UK motorists looking for compensation, Parker said: "There are spikes when there is a lot of media around VW, in particular when there is good news for US car owners and bad news for UK consumers who understandably feel that they are being treated unfairly."
Mary Creagh, chair of the Environmental Audit Committee, said: "It's been a year and a half since VW was caught deliberately fitting cheat devices to their cars to fool regulators, and the latest figures show only about a quarter have been fixed."
In the absence of any action by the government, motorists have been left to take matters into their own hands.
"My committee has called on ministers to get on with measuring the contribution that VW’s cheat devices made to meeting UK emissions standards, and use the results to take court action against VW," she added.
Around 1.2m vehicles in the UK are said to have been affected, but Parker thinks the number of affected car owners could be greater still.
"There has also been a growing realisation that you can claim even if you have sold your car, had the so-called fix, or if you bought your car second hand," he said.
Because cars change hands every few years, the number of affected car owners could be north of 2m, based on the 1.2m affected cars.
The owners of VW, Skoda, Seat and Audi cars have all been affected.
The UK consumers won't have to pay for the legal costs either, as Parker said the firm had secured funding from Therium Capital management "who are paying for all of the costs".
A spokesperson for the Department for Transport (DfT) said:
"The government takes the unacceptable actions of VW extremely seriously. That is why we have taken swift action to protect the UK consumer. We were the first country in Europe to complete our own tests (April 2016) to ensure the issue was not industry-wide.
“We continue to push VW to take action to compensate the UK consumer. Transport minister John Hayes has met with Volkswagen on several occasions and pushed them to offer compensation every time.”
Volkswagen Group UK said:
Only a very small number of customers have expressed interest in taking legal action against us in England. The vast majority of our customers that are affected by the NOx issue are satisfied with the actions that we are taking.
"We have said all along that we will robustly defend any litigation that is brought against us in England, and we have made it clear to the claimant law firms that we do not anticipate that any of our customers will in fact have suffered any loss as a result of the NOx emissions issue. The vehicles are safe and roadworthy, and perform as advertised."
The company said the instigation of legal proceedings was also "premature for a number of reasons, not least because the implementation of the technical measures in the affected vehicles is still ongoing".
It comes as the chair of the Transport Committee, Louise Ellman, called on VW UK's managing director to provide more in-depth answers on matters such as costs and information requested by the DfT and fixes for vehicles.
Ellman said in a letter to VW's UK boss Paul Willis that evidence he provided at a Transport Committee meeting last month "fell short of our expectations in a number of ways", and some was "not credible, incomplete, intended to mislead and may have fallen short of the truth".