Apr.3 (GMM) New Zealand racer Brendon Hartley on Thursday confirmed that he recently conducted the secret track debut of Toro Rosso's new car, the STR3.

It emerged this week that, with the Italian team's race drivers Sebastian Vettel and Sebastien Bourdais overseas for the Malaysian and Bahrain grands prix, the task of shaking down the car fell to the highly rated Red Bull junior driver.

Hartley, 18, drove the Ferrari powered STR3, that is based on Red Bull's Adrian Newey penned RB4, at the Vairano circuit in Italy.

The current British F3 competitor, who last year became the youngest ever winner of the Formula Renault 2.0 Euro Cup, has also driven a Renault-powered Red Bull F1 car in a demonstration in Saudi Arabia, after familiarising himself with the machine over a few laps at Silverstone.

"There's been a lot happening in the last few weeks that I haven't been able to speak about," Hartley is quoted as saying by the New Zealand Press Association.

"The formula one testing with Toro Rosso was a confidential development session for a car that is yet to be publicly launched," he added.

"What I can share is that it was a privilege to be invited to drive the new car for the first time," Hartley said.