Formula One's Kers power-boost systems could make a comeback next season in a cheaper and more powerful guise.
Ferrari and Renault have offered to supply the systems - scrapped by teams last year for cost reasons - at lower prices and with higher energy levels.
"Renault will supply anyone who asks for it on the grid," said Williams technical director Sam Michael after a meeting of the teams' association Fota.
"Ferrari will supply any anyone who is running a Ferrari engine."
Kers systems are similar to those that are becoming increasingly widespread in road cars, with Toyota, Honda and BMW among those already marketing so-called "hybrid" cars.
They work by storing energy that would otherwise be wasted as heat during braking and re-applying it to either boost power or cut fuel consumption during acceleration.
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But Kers, the subject of controversy in 2009, was eventually abandoned on cost grounds. The teams using Kers - McLaren-Mercedes, Ferrari, Renault and BMW - are estimated to have spent a total of £40m on developing the system.
And it is widely believed that the 2009-spec Kers did not provide a big enough boost of power - they were limited by the rules to dispensing 400 kilojoules of energy a lap.
Now, according to Michael, Ferrari and Renault are offering a less expensive and more powerful version.
"Ferrari and Renault put forward proposals that they could do Kers for less than 1m euros (£869,000)," 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."
Although Kers remains in the regulations, with governing body the FIA 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 season.
Brundle and McLaren explain Kers
"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.
Williams, who own 78% of a hybrid power company developing flywheel technology, would expect to use their own systems.
Meanwhile, the Fota meeting also discussed the 2011 tyre 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 tyres.
"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."
Ferrari boss Stefano Domenicali suggested after the Chinese Grand Prix that a tyre deal could be announced before Barcelona, but 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 tyre supply."
