Another piece of the 2009 formula one grid fell into place on Wednesday, when McLaren debuted a front nose and wing conforming with next year's radically altered bodywork rules.
BMW-Sauber, Williams and Honda have already tested visible elements of the 2009 regulations, including the front wing, which is notably wider than in 2008.
The task of testing McLaren's new wing at Jerez fell to test driver Pedro de la Rosa, whose MP4-23 was fitted with a 2008 rear wing.
"The evaluation was extremely positive," McLaren said in a statement.
Also at the Spanish circuit on Wednesday, local Fernando Alonso drew crowds with his first appearance of the winter, but while he was trying slick tyres, he ran off the circuit and clipped a barrier.
"It was nice to run on the slick tyres as they are more grippy, but when you lose the downforce from the car they don't feel massively different to grooved tyres," he said.
The 27-year-old will again be on duty on Thursday, for Renault's last day of testing in 2008.
Other notable contenders in action on Wednesday were both Ferrari and BMW-Sauber's 2009 race drivers.