Renault's Robert Kubica has praised his car's newest asset, its F-duct system, after two successful practice sessions on Friday.
The Pole was as high as second before settling for fourth in practice, two-tenths of a second behind the fastest time set by Fernando Alonso.
It will be the first time Renault have used the F-duct device this season, which will be beneficial on the long straights of the Spa circuit, reducing downforce and allowing the car to reach higher speeds.
Kubica said despite the wet weather in practice, the car held up well.
"It was quite a good Friday for us," Kubica said.
"The conditions in first practice were pretty bad but our main aim was to check how the F-duct system was functioning on our car."
"We focused on getting experience of the system, for the engineers and for myself, and to get everything working properly - and we managed to do this in spite of running in the wet."
The F-duct proved its worth through Spa's speed traps, with Kubica's Renault clocking six kilometres per hour quicker than any rival on that part of the track.
Kubica said his team also trialled all tyre types on the wet track at Belgium, leaving no stone unturned to propel Renault back onto the podium.
"In the second session, I ran every type of tyre: extremes (wets), Intermediates and both compounds of the slicks. The car felt reasonable in all conditions but I think we can make further improvements to the balance tomorrow (Saturday)," he said.
Kubica is eighth in the F1 drivers' championship on 89 points going into Sunday's Grand Prix.