McLaren is in a bit of a weird situation when it comes to identifying major improvement points from last year just because they started out so bad in 2023.
That means half the races from 2023 are irrelevant data points because we would be comparing a literal backmarker to a (at worst) top 3-4 car when it wasn't actually the best.
The other remaining races unfortunately have mismatches in terms of weather conditions. Some just because they have vastly different air and track temps, others because of rain and the rest because the races itself were organized on different periods of the year.
One of the closest comparison points to last year was actually Abu Dhabi, the last race of the season.
Weather conditions when the fastest lap in qualifying was set in 2023 and 2024 are both quite similar with negligible differences, even in terms of wind speed :
(2024 top, 2023 bottom)
From that comparison, the most noticeable improvement is at medium-low speed corners. The 2024 car not only is capable of maintaining higher minimum speed through those, but it also "bleeds" less speed on longer corners. In fact, when compared to the rest of the 2024 field, long medium-speed corners is perhaps the one area where McLaren excelled, with performances in Zandvoort (especially with the strong S2 there) being one of the many examples of their advantage.
This is a contrasting comparison with their 2023 car, because those types of corners were their biggest weakness last year after the Austria upgrade transformed the car. They have showed great understanding of their package and the regulations from that point onward, with upgrades that have clearly addressed the weaknesses that were faced on-track.
Although qualifying is a good indicator of overall improvements because you're judging peak pace, I would argue a significant improvement over 2023 for McLaren was their race-pace and how well they could look after the tires, although this trait of the car could not be exploited by Oscar as often as it was by Lando.
Still, if you look at the 2024 season, their tire wear performance in race pace was probably only second to Ferrari, which paid a significant price in quali-pace for that tire wear advantage.
When looking at the race lap-chart between the 2023 and 2024 car at Abu Dhabi, one can very clearly see how much more consistent the 2024 car is throughout the stint, losing very little pace (comparatively) towards the end of the stints. What's somewhat bizarre is that the 2024 car at some cases even displayed "negative degradation" if one can call it that. Basically, the laptimes were getting faster by the end of the stint instead of getting slower.
2023 :
2024 :
Although McLaren made huge improvements from 2023, there were areas of the car which they did not manage to improve. The biggest of which was drag, or overall straight-line performance. Because a lot of attention was given to rear wing + beam wing configurations throughout 2024, we can assume that downforce efficiency was perhaps vastly improved over 2023 (RW-BW wise), however the overall straight-line speed performance in comparison to the competition was still quite weak.
Since the car also lost some of the high-speed corner advantage in 2024 (which is highly likely to be an accepted compromise for the improved medium-low speed performance), this lack of straight-line performance is perhaps not as simply correlated to high wing levels, but rather a draggy concept.
To sum up, McLaren did an amazing job in 2024 to fix the most damning weaknesses of the 2023 car so quickly, but there is still room for improvement. It seemed like towards the end of 2024, the car was receiving little significant developments, but some post-season articles have hinted towards them holding back certain ideas for 2025.
Development potential aside, the major weakness points that need to be addressed for 2025 (in my opinion) are :
1 - Straightline performance / Drag
2 - Wet weather performance (and actually, in general, improvement in lower temps)
3 - Performance in quick changes of direction
