Lewis Hamilton has claimed he has no intention of driving the W13 again once the current F1 season has finished after the final qualifying of the season in Abu Dhabi saw a return of old issues for Mercedes.
The seven-time champion qualified fifth for the race at the Yas Island circuit, two-tenths of a second slower than fourth-placed Carlos Sainz and almost seven-tenths adrift of Max Verstappen's pole lap.
It was a heavy landing for the Silver Arrows after the elation of victory in Brazil a week ago, with team principal Toto Wolff describing qualifying as a "toilet day".
"I definitely wasn't expecting to see such a big gap, but we are losing six-tenths on the straights," said Hamilton.
"Kind of reminiscent of some of the previous races before Austin. And bouncing is back, it is not easy."
Mercedes was left fighting in a world of its own for the first half of the season as drag-efficiency and porpoising problems set back the team's development plan.
On his wishlist for the winter break, Hamilton, who will drive the W13 for a final time in the post-season test, insisted: "We have obviously got some downforce, we just need to build a more efficient car.
"I think everybody in the team knows what are the problems and where we have gone wrong.
"Pretty confident they are not going to build the next car with any of those characteristics.
"I am looking forward to the end of Tuesday, which is the last time I drive this thing and I don't ever plan to drive this one again.
"It won't be one of the cars I request to have at the end of a contract."