Feb.27 (GMM) Sebastian Vettel says he was happy with the opportunity to test Red Bull's new car for 2008, the RB4, on Tuesday.

The German youngster, called up to replace David Coulthard at Barcelona after the Scot trapped a nerve in his neck, completed 110 laps in the Renault-powered car.

Vettel will race a similar version of the RB4 later this year when Toro Rosso, the second Red Bull team, gets its STR2 up and running around the time of the Turkish GP in May.

"For me, this was a good opportunity to get a feel for what we can expect later in the season," the 20-year-old told Auto Motor und Sport.

Vettel added that he thought the RB4, and therefore Toro Rosso's new single seater, has "genuine potential".

Coulthard is expected to return to the cockpit on the last day of winter testing on Wednesday, but Vettel is standing by in the event that the Scot is not fit.