New Delhi: Ahead of the new racing season, former Formula 1 driver David Coulthard has said that two-time World Champion Fernando Alonso's new deal with McLaren, which was in the air for some time, is a "marriage of convenience".

Alonso left Ferrari at the end of the last season after spending five years at the Maranello-based outfit, to join McLaren for whom he raced during a turbulent 2007 season.

"Alonso did not have a choice. Ferrari got Alonso to sign the release to leave the team early and he went right across to Mercedes where there was no space. So he ended up at McLaren... it is a marriage of convenience rather than desire," Coulthard told IANS in an interview over the phone from London.

"With Honda, a former World Championship-winning engine-designer, Alonso hopes they will be able to provide a power unit that can give McLaren the chance of winning races again. If they win races, then Alonso can aim for the world title," added Coulthard, who took part in 247 Grands Prix.

McLaren, who have not won a race since 2012, ended their engine partnership with Mercedes after 20 years, to partner Honda, with whom they won four consecutive constructors' championships from 1988 to 1991.

The Scotsman, who has to his credit 13 GP wins in a career spanning from 1994 to 2008, spent the winter making a documentary, showcasing the rise of Mercedes as the most dominant team of 2014. Coulthard believes the 'Silver Arrows', who won 16 of 19 races last season, will be once again the team to beat this year.

"Mercedes will carry the momentum into 2015. If you look historically, whether it was Ferrari during their dominant period, McLaren or Red Bull, the performance advantage over your competitors gives you the luxury of starting development while the other teams are still trying to catch up," said Coulthard, who will be hosting the three-part documentary 'F1: Behind the Wheel' to be shown on BBC World News Feb 14 onwards.

"The key element for them is their hybrid power unit which is by far the strongest and which will be at an advantage among units of Renault, Ferrari and Honda. Other teams will close the gap but the momentum will be with Mercedes unless they have a fundamental flaw aerodynamically in their car. Their power advantage should enable them to get multiple GP wins."

When it comes to the drivers' championship, Coulthard, who raced for Williams, McLaren and Red Bull during his F1 career, added that Nico Rosberg will come out stronger in 2015 to challenge teammate and reigning World Champion Lewis Hamilton.

The Mercedes teammates reigned in 2014 but Hamilton, with 11 victories, became World Champion for the second time over Rosberg, who could muster only five wins.

"Nico will be stronger than he was last year, considering he has analysed his performance in the winter and see where he can improve. If he has not, then he will not be a World Champion because I am yet to imagine a guy who has gone on to win at that level and isn't thinking about his performance at every moment," said the Scot, who finished runner-up to legendary Michael Schumacher in the 2001 drivers' championship.

"Both drivers have the same data which they get from the team but the one thing that separates them is racing instinct. What will be interesting to see is whether Nico will be able to fine-tune his racing instinct into making good decisions that Lewis does in wheel-to-wheel combat."