Smiles turned to consternation in the Red Bull garage on Wednesday after the RB6 was launched in the pitlane.
After a mostly wet morning at the wheel of the new Renault powered car, Mark Webber had to walk back to the pits after it broke down with an oil leak.
The team said the stoppage was actually "precautionary", and Australian Webber also played down the problem as being "nothing major".
The RB6 is clearly an evolution of the highly competitive 2009 car, but its double diffuser is clearly new, as the rear device was carefully covered during the launch.
Also notable was the presence of the former Renault sponsor Pepe Jeans on the livery.
Sebastian Vettel, watching on from the pitwall on Wednesday, said he is yet to give the car a personal name, after last year's RB5 was humorously called 'Kate's Dirty Sister' because it was faster than the 2008 car, 'Kate'.
Webber was yet to set a front-running time by the time of the oil leak.
Mercedes' Nico Rosberg was consistently quick throughout the opening morning of the Jerez test, ahead of the Toro Rosso (Sebastien Buemi) and Williams (Nico Hulkenberg) cars.
Fernando Alonso was fourth quickest for Ferrari, ahead of Kamui Kobayashi (Sauber).
Jenson Button's new McLaren was featuring a bizarre and huge sensor attached to one side of the cockpit, but the British team said it did not indicate an aerodynamic problem.
Tonio Liuzzi gave Force India's VJM03 its proper test debut, and at the time of writing, Timo Glock had only just exited the pits at the wheel of the new Virgin.