Williams technical director Sam Michael told Reuters after a meeting of the teams' association FOTA on Wednesday that Ferrari and Renault had offered to supply systems at affordable prices.
"Basically Ferrari and Renault put forward proposals that they could do KERS for less than a million euros ($1.33 million)," said the Australian.
"Those have been accepted but what Ferrari and Renault are both saying is that unless we increase the energy level from the current 400 kilojoules up to 600 or 800, to make KERS more beneficial, they are not prepared at this stage to commit that they will actually do KERS." The old kinetic energy recovery systems, which stored energy generated under braking to give drivers a short boost of power at the push of a button, helped McLaren and Ferrari win races last year but cost 10-20 million euros to develop.
Although KERS remains in the regulations, with the governing body backing the systems as relevant to ordinary road users and important for the sport's environmental credentials, teams have agreed not to use them this year.
"I think that by Barcelona (next week's Spanish Grand Prix), the FOTA executive is due to try and make a decision on KERS for 2011. It's all pretty split at the moment on that," said Michael.
"Renault will supply anyone who asks for it on the grid and Ferrari will supply any of their customers, anyone who is running a Ferrari engine," said Michael.
Williams, who own 78 percent of a hybrid power company developing flywheel technology, would expect to use their own.
The FOTA meeting also discussed the 2011 tire supply, with Bridgestone pulling out at the end of this season.
"The conversations really, at this point, are between Michelin and Avon," said Michael.
"Avon's a lot cheaper (than Michelin) but it's a less proven product although they've done plenty of highly competitive tires.
"They are a bigger unknown than Michelin because Michelin did it (in F1) very recently. But there is a significant difference in cost and you are probably talking over three times the difference in cost to the teams. So that's what's being debated at the moment." While Ferrari boss Stefano Domenicali suggested after this month's Chinese Grand Prix that a tire deal could be announced before Barcelona, Michael said that looked unlikely.
"I think the discussion in FOTA is just acknowledgement that you've got to take into account a lot of different factors, it's not a straight financial decision and it's not a straight technical decision," he added.
"All this needs to be discussed with (F1 commercial supremo) Bernie (Ecclestone) as he's traditionally looked after tire supply." Former champions Williams, with experienced Brazilian driver Rubens Barrichello and German rookie Nico Hulkenberg, are just seventh of the 13 teams with just six points after four races.
Hulkenberg even finished behind Finland's Heikki Kovalainen, driving for newcomers Lotus, in Shanghai on April 18 but Michael dismissed the significance of that and said better times were coming.
"We've got a lot of stuff coming to the car over the next three or four races, particularly aero-dynamic performance parts which is always the quickest and most effective way of adding performance to the car," he said.
For Spain, there will be a new front wing and possibly a redesigned rear diffuser that had been set for introduction at Monaco, a week later.
"I would say by Monte Carlo, the second race from now, we should have taken a good step and then we've got a pretty steady stream past that," said Michael.
