AN Italian consumer group is inviting car buyers to join a class action lawsuit against Fiat and Volkswagen over allegations that the companies exaggerated fuel-saving credentials of their vehicles.

After conducting tests on Fiat's Panda 1.2 and Volkswagen's Golf 1.6 TDI models, Altroconsumo said the models were between 18 and 50 per cent less fuel efficient than stated n marketing and sales material.

The consumer group is asking Fiat to pay compensation of 247 euros ($320) to each buyer of the Panda model and of 509 euros to owners of the Golf model tested, based on what it estimates to be additional fuel costs for an average annual distance driven of 15,000 km (9,320 miles).

"Consumers buying supposedly efficient cars are misled too often," Monique Goyens, director general of the European Consumer Organisation, of which Altroconsumo is a member, said in a statement.