Alonso started 2023 with a run of podium finishes and was occasionally the closest challenger to pacesetters Red Bull.
However, in the middle of the season, Aston Martin took some wrong steps in development, and the team slipped down the order before a resurgence late in the year.
Alonso believes that his team won't repeat those mistakes and has addressed them with its new car.
"I'm confident," he said. "If not, I could not maybe sleep for the last two months! But I think we did a lot of experiments and a lot of changes back and forth in terms of understanding the problems and the direction and the paths that we need to follow this year on the car.
"I think we understood a lot of things, and with this year's car we intend to improve some of those weaknesses that we saw in terms of developing the car last year that we maybe got into the wrong direction a few times, and we understood a little bit too late.
"Hopefully we have that knowledge, those difficulties from last year were lessons that we took on board for the '24 car, and we will see the result.
"I think we had a good step forward this winter, maybe not as big as last year, because last year the baseline was very poor. And this year, the baseline was very strong already last year's, which is understandable."
Alonso made clear in what areas he expects to see improvements with the new car relative to the AMR23, which had inherent weaknesses despite its strong form.
"I basically will love to have a little bit more downforce," he said. "Especially on the high-speed corners, probably it was one weak area last year, that I think we tried to improve in this year's car.
"Top speed was not the best last year; we were always fighting on the straights. And we were on the bottom of the charts always on the top speed. So we tried to be a little bit more efficient this year, a little bit faster on the straight.
"So there are a couple of points that I would love to see in the car when we hit Bahrain winter testing, which probably will help us on Sundays on the race weekends."
Alonso also stressed how close he expects the field to be, with marginal gains likely to make a big difference relative to rivals.
"I know that it's going to be very tight," he said. "So, even if we make a reasonable and very good step forward, we know that the other teams, over the winter, do also a good step forward.
"And we saw in Abu Dhabi, I think within six tenths it was pole position and P18. So when you improve a couple of tenths, this can change your life. And this can change fighting for the podium or being in Q2, out of the top 10 in the first races.
"And it's just one small update that maybe you bring to the next race, and from Q2 you jump to a podium. So I think it's going to be a very interesting season, and a very demanding season off-track, trying to bring upgrades to make a difference."
Additional reporting by Jonathan Noble
