The alliance between PSA Peugeot Citroen and General Motors already has teams working on how it will develop.

"We began some months ago discussing specific cooperation," said Frederic St Geours, PSA vice president. "Then we started asking why not have a strategic global alliance?

"Then we said that if we did it had to be balanced because unbalanced alliances fail."

Teams started working last week on areas where the alliance can be moved forward with joint purchasing and model development the immediate priorities.

St Geours highlighted the failed Fiat-GM alliance as a good example of one that was unbalanced. "There is no risk of us repeating that. The cultural fit is good and it only took us a few months to put it all together."

He stressed that the alliance is not about the industrial sides of the companies - who builds what, where - but about purchasing and model development.

PSA currently spends YS$35bn a year on purchasing; the alliance will spend $125bn a year. PSA buys 2m tonnes of steel a year; the alliance will buy 8m. That buying power puts PSA and GM in a very strong position, he said.

The two companies will also progressively develop platforms together; initially these will be B, D, crossover and minivan platforms with the first joint platform expected by 2016.

The alliance will also help PSA accelerate its globalisation "Europe is weak so this is even more relevant for us today," he said. "We will be able to globalise at reduced cost and better time to market."

St Geours added that PSA was already very experienced at sharing platforms between Peugeot and Citroen; there is 60% commonality between Peugeot and Citroen products (except for the C1/107 built in partnership with Toyota) "and I'm sure we will be able to do the same with GM".