Although they admit it was low fuel run on supersoft tyres, so still hard to judge who really had speed at Jerez as Schumi's 2nd place run was on a 10 lap fuel load and undisclosed tyres, but with KERS and flappy wing assistance at every opportunity.
Williams have denied that Rubens Barrichello's quickest lap during the Jerez test was set with an underweight car. The Brazilian's best time was over half a second quicker than the second best lap, set by Michael Schumacher on day two.
Rumours circulated the paddock with an unnamed driver claiming they must have been running underweight by removing the KERS system. If true, it came just days after the team announced their plans to go ahead and float on the stock market.
The teams technical director Sam Michael has denied the rumour as 'absolute nonsense.'
"This time was real. Anyone who knows our team knows that we do not run underweight," he told Auto Motor und Sport.
Michael explained that KERS was simply disconnected after the team encountered some overheating issues, otherwise the time was down to the super-soft tyres and low-fuel.
"Rubens time is down to the super soft tires, he of course had a little less fuel in the tank but the KERS elements were all on board, we had only cut the connection from the generator to the engine and all the batteries remained in situ. This was because we had an issue with cooling."
When asked why the team had languished in the lower mid-field for the early part of testing, Michael highlighted the medium tyres as an issue which they had yet to understand.
"This is because we had only used the medium tyres and always with a relatively large amount of fuel on board. We never got the medium tyre to work and we're still unsure of why."
The F1Times.com, Today.