Berger insists new Toro Rosso is legal

The new car is designed by Briton Adrian Newey, who also penned the Renault-powered RB3 of sister team Red Bull.

The likely similarities between the two have already prompted threats of legal action from rivals in Melbourne, with the rules stating teams must design their own cars and own the intellectual property rights.

"It's definitely not the same car," Berger told reporters during a launch event at Barcelona. "It's very easy to see that. It's not just the engine, a lot of stuff is different.

"There is a different interpretation of the Concorde Agreement and I respect very much the interpretation of Spyker and Williams but we have a different one," he said, referring to the confidential agreement between teams, governing body and commercial rights holder.

"We checked it very carefully before we even went down this road and we got from different sources always a very clear understanding we are inside the rules."

Berger, whose team finished ninth overall in 2006, said it was too early to say how competitive the new car would be.

"It's a big challenge for us to operate this car because it's very different to the one we had before but we are confident we can make the next step forward," he said.