Auto industry expert Garel Rhys has leant his support to the unions' plan to keep Peugeot's doomed plant at Ryton open.
Professor Rhys, director of the Centre for Automotive Industry Research at Cardiff Business School, was asked to study the alternative scheme to keep Peugeot manufacturing in the UK, which was put forward in May this year.
The proposal involved moving to a single shift at Ryton from July, reducing costs at the plant and building a new undisclosed product in 2009/10 on two or more shifts.
As joint union representatives met with PSA Peugeot Citroen executives yesterday, Prof Rhys said the carmaker should treat the alternative plan seriously.
He said Peugeot's attempts to justify the Ryton closure were damaging not just the auto sector but also the international perception of UK manufacturing as a whole.
Prof Rhys said: "The trade unions alternative business case for Ryton has very powerful reasons why it should be treated seriously by Peugeot and other interested parties.
"The unions are offering a dramatically innovative package of new working practices which would result in significant increases in efficiency and productivity which would reinforce Ryton's already impressive performance and profitability.
"Independent figures show that Ryton's output per man at full production is one of the best in the PSA empire.
"This together with the damage that PSA has done to the cost per car by reducing Ryton's plant utilisation since 2003 leaves one sceptical about their calculations concerning cost penalties in the UK."
Prof Rhys said with the right product and attitude other car makers have shown what a good production base the UK can be.
He said Peugeot's attempt to justify their retreat is damaging not just to the auto sector but also the international perception of UK manufacturing as a whole.
Meanwhile the advantages of moving to Slovakia, where Peugeot will begin building the new 207 car at a factory in Trnava, would be short-lived.
He said: "The torrent of investment into Slovakia which means by 2010 they will make more cars per head than any other country indicates a pressure on resources of all kinds but especially labour.
"Consequently the country is likely to experience much worse wage inflation than the UK so the main attraction of Slovakia will be short-lived.
A customer boycott could also hurt Peugeot, Prof Rhys added: "The nature of PSA's intended evacuation from the UK is quite different to other recent plant closures.
"The contribution of Ryton to PSA's profitability other the last 25 years demands that they show a willingness to cooperate in any efforts to retain what is a viable, sustainable and profitable plant."