Mercedes: Fourth engine supply unlikely

In the build-up to the Canadian Grand Prix, Mercedes GP team principal Ross Brawn reckoned that his parent road car company was 'on the limit' in terms of working with other teams, and he urged caution before a decision was taken to add another outfit to the roster.

Mercedes-Benz motorsport boss Norbert Haug has echoed Brawn's comments and thinks that, with the works team likely to run KERS next season, it may have too much to work on for it to be able to add another customer.

"We have probably KERS next year, so we need to look at our capacities," said Haug. "It definitely would be very difficult for us to supply a fourth team - but no final decision is taken yet.

"We have cut the workforce on our engines, and we also need to prepare in a while for 2013 when there will be new rules. So probably the best decision is to stick with three teams.

"That is not the final decision taken, but probably we will stay as we are."

Although Red Bull Racing has enjoyed great success with Renault, team principal Christian Horner said recently that his team's decision on which power-unit to use in 2011 could well rest on engine parity parameters laid down by the FIA.