Fernando Alonso believes his McLaren-Honda team has "logical" solutions that will bring more than the two-second performance gain it wants from its 2016 Formula 1 challenger.
Honda endured a torrid return to F1 with McLaren in 2015, racking up a string of failures and generally being mired in the lower midfield.
The Honda V6's inability to deploy as much regenerated energy as its rivals left Alonso and Jenson Button facing big straightline speed deficits in grands prix.
Alonso insisted in October that McLaren could close the gap to the front by as much as two seconds over the winter, and asked if he still held that opinion, he replied: "I'd agree with that.
"I think it will be relatively more than that."
Alonso said the improvements will come from "everywhere", adding: "We have not been optimising the car in some parts of the year.
"We're a bit clearer with what the strengths of the car are and we need to exploit a bit more in that direction.
"We know the power unit has been our main limitation, so there are no radical changes for  in terms of [car] design and philosophy.
"We know the deficit we have on the straights compared to other cars.
"So if we apply some of the solutions and everything is working as we expect, the laptime benefit will be very big.
"There are solutions in place which are logical and quite good and keep the motivation very high because I think  will be a completely different picture.
"We have been through some difficult times, but I think we learned from it.
"We have kept united, working in harmony and that was the positive thing.
"The negative thing has been the results."
Although Alonso acknowledged that the whole field would improve before 2016 begins, he still believes McLaren's potential for gains is much larger.
"Everyone will improve between 0.5s and one second," he said.
"With us being two seconds off the pace, we need to do more than 0.5s or one second.
"The power unit will be the main thing to unlock this potential."