The motorists believe they were misled by Volkswagen over its diesel emissions after the company admitted it used special devices to cheat tests.
It has now been suggested there are 1.3m engines of the type affected in the UK, although it is not yet clear if the emissions software is running in all of them.
Slater and Gordon Head of Group Litigation Jacqueline Young said: “More than 500 people have contacted Slater and Gordon in the past two and a half days to register their interest in signing up to a group action against Volkswagen.
“On Monday morning our website was receiving two enquiries a minute from people trying to register with us for more information.
“The level of outrage among ordinary people is unprecedented. It’s understandable that diesel car owners want to stay up to date on this scandal.
“We are calling on Volkswagen to urgently provide clarity on exactly the extent of the problem. We seek confirmation of which models and makes are affected by this scandal and to what extent. Were defeat devices installed across the board and if not, what selection criteria was used?
“VW must also come clean about how long the practice has been on-going and who within the executive authorised or condoned this practice.
“Trust in the VW brand has all but been eroded, but now is the time for the company to urgently provide clarity on these issues which impact large numbers of the UK public who have been completely misled.
“Affected car owners are potentially out of pocket and have a car which might no longer meet their requirements. It is vital that those affected have a full picture from VW of exactly what has gone on.”
“To register for more information about a potential group action, please visit Volkswagen CO2 Emission Scandal Legal Investigation.
Jacqueline Young is Head of Group Litigation at Slater and Gordon Lawyers UK.
Follow Jacqueline Young on Twitter for live updates on the VW scandal @jacyounglawyer