Senior executives of Ford, GM, DaimlerChrysler and Renault/Nissan were at the Geneva motor show this week briefing dealers and suppliers on why they have formed the world's largest virtual marketplace.

Ford, GM and DC, which spend £150bn annually on supplies, announced the internet-based scheme, intended to simplify buying and drive down costs. Renault/Nissan confirmed plans 24 hours later to be part of the independent company; other carmakers have also shown an interest.

Earl Hesterberg, Ford of Europe head of marketing, sales and service, said in Geneva: “We can all reduce development expenditure by agreeing on a simple design 'language' for components which do not directly affect a brand.”

The joint venture, likely to be floated and extended to other industries, is subject to government approvals; it could be viewed as too powerful.

Harold Kutner, in charge of GM's worldwide purchasing, said: “We are going to create the world's biggest, fastest, largest exchange for transacting business that the internet or probably any other businesses have seen.”

For dealers, the planned venture will add to concerns about carmaker power and worries over their long-term role.