Gerhard Berger believes Lotus don't have the financial strength to compete with Red Bull and Ferrari over the whole year
The Finn, and his Pirelli-gentle Lotus car, are currently Sebastian Vettel and Red Bull's closest challengers in the drivers' and constructors' tables.
Berger told Auto Motor und Sport: "Kimi is sitting in a very good car at the moment.
Red Bull and Ferrari over the whole year.
"He will make it uncomfortable for them, he will win races, but he won't fight for the world championship."
Indeed, former Toro Rosso co-owner Berger, 53, tips a "close fight" for 2013 spoils between Vettel and Ferrari's Fernando Alonso.
The Austrian was also asked about F1's controversial tyre situation, commenting: "You can see it both ways.
"Basically, it's the same for everyone, and looking after tyres was always an issue, although maybe not quite as dominant as now.
"On the other hand, it makes little sense putting millions into developing cars and engines if the tyre just determines everything.
"And if he who looks after the tyres best is the winner, then there is a problem. Everything can be overdone.
"I thought 2012 was a better compromise," Berger added.