Force India has said that it is still working on its 2018 car, after a difficult start in Melbourne.

Despite finishing fourth overall in 2016 and 2017, the Silverstone-based team has fallen behind the highly competitive midfield this year.

However, technical boss Andy Green told Auto Motor und Sport: "Not everything has arrived yet.

"We still have a problem from the apex to the corner exit right now."

Deputy boss Bob Fernley agrees that Force India is still working to improve the new car.

"It will take two to three races to understand the package. We will have a new wing in Bahrain."

Driver Sergio Perez said: "We will soon be back in a position to fight for points."

Explaining the difficult start, Fernley said that one factor is engine power.

"Compared to Melbourne 2017, the Mercedes teams improved by an average of 1.1 seconds. Unfortunately, the Renault teams have improved by 1.6 seconds. And that's exactly who are opponents are."

Fernley is referring to McLaren but also the Renault works team, adding: "They not only have more money and people than us, but also excellent drivers.

"That makes it all the more important that we show the same qualities as last year - consistency, reliability, and good strategy. In 2017 we had the fourth fastest car in very few races and nevertheless finished fourth," he said.

The 2018 season continues next weekend with the Bahrain Grand Prix.