George Russell compared the Mercedes W14 to "a lame horse", following on from previous criticism of the car by his team-mate Lewis Hamilton.
Last month, Hamilton called out his team in public, accusing them of not listening to his input on the design of the car. He later said he probably should have used different words, but is still "miserable" about working with a car with which he says he has no connection.
He later complained about his seating position in the W14, which he feels is too far forward. Responding to that particular problem, team principal Toto Wolff said it was something they would be working on as he sent a message to his staff.
"We are dealing with the big concept of the driver position. That is obviously one of the most important things," the Austrian said. "It's about where the driver has the best feeling in the car, which is something Lewis expresses very clearly. And when a seven-time world champion has an opinion, it is important to listen to it."
Russell joined Mercedes last year from backmarkers Williams – a move which coincided with the Silver Arrows' performance decline. Instead of competing for regular race wins and the championship as expected, he and Hamilton have had to scrap for all the points they can get ever since.
It was hoped that the W14 would be the machine in which Mercedes would return to the very front of the grid, but that has yet to happen. Sticking with that horse analogy, Russell told German publication Bild that getting used to the Mercedes car was also like a steed getting used to a new rider.
He said: "It is comparable to riding a horse. A Mercedes is a faster horse than a Williams. But it's not just about speed. Riding a horse from A to B and it doesn't zig is like sitting in a Formula 1 car that suits your driving style. One merges into another.
"At the moment, however, we have a lame horse. We know that it has a lot of performance in it, but it is not happy that someone wants to ride it and the way of riding style does not suit him either.
"It still has its own head, which sometimes runs the risk of throwing you off. We still have to get used to each other and develop it so that it becomes fast and tame."
