[7] Technical Director James Allison labelled the W15 project as "ambitious" and stated the team had made a lot of progress over the winter.

[8] Allison later clarified that the late introduction of sidepods starting from the 2023 Monaco Grand Prix wasn't the main shortcoming in 2023, and added that the W15 would look significantly different from its predecessors.

The car sported a mostly bare carbon fibre and black livery, though with a silver nose cone and their title sponsor Petronas's teal as an accent.

[16][17] The team ended their pre-season testing on a good note with both drivers finding the car much more stable and more predictable compared to its predecessor.

[22] Hamilton gambled by not pitting due to an early safety car, running as high as third and defending against Oscar Piastri for 20 laps.

[24] Hamilton retired early due to a power unit failure while Russell crashed out in a penultimate lap incident with Fernando Alonso.

[28] During the sprint race, Hamilton overtook polesitter Lando Norris in the first corner and held the lead for a couple of laps before he was overtaken by Verstappen.

[32] In the sprint, Hamilton was penalized by the stewards with a 20-second time penalty for speeding in the pit lane during a Safety Car period, dropping him to 16th.

[34] Mercedes brought upgrades for the Emilia Romagna Grand Prix consisting of a revised floor and brake duct, and a new rear and beam wing.

Russell pitted late for a new set of mediums, effectively swapping positions with Hamilton, with the former finishing behind, but with the fastest lap at hand.

[41] Hamilton would later criticise his race as one of the worst of his career for failing to capitalise on the car's competitiveness in Circuit Gilles Villeneuve.

[44] Mercedes locked out the front row in the British Grand Prix, with Russell qualifying on pole and Hamilton in second.

Hamilton held off Verstappen and Norris in the changing conditions en route for his first victory since the 2021 Saudi Arabian Grand Prix, ending his winless streak of 56 races in two seasons.

[49] For the Dutch Grand Prix, Russell qualified in fourth place, while Hamilton ended up in eleventh after a mistake during his final Q2 run prevented him from advancing to Q3.

Russell, who was running in fifth, was forced to make a late pit stop to defend against a charging Carlos Sainz Jr.

[52] In Italy, Russell qualified third, but due to a mistake and running wide at turn one, he lost positions and damaged his front wing.

[56] Mercedes utilised a special livery for the Singapore Grand Prix to celebrate the 50th anniversary of the team's title sponsor, Petronas.

Mercedes were the only top running team to implement split strategy for both of its drivers, with Hamilton in softs and Russell with the mediums.

[59] Following the race, Mercedes confirmed that they will bring their last "substantial" upgrades to Austin and learning how to run under tracks that are prone to overheat the tyres.

[62] Hamilton blamed the upgrades after he qualified 19th for the main race and retiring early after he spun out into the gravel trap at Turn 3.

The approach ultimately paid off as Russell finished the race in sixth aided by a late overtake on Pérez, despite the stewards penalising him with a 5-second penalty for the manner he overtook the Sauber of Valtteri Bottas.

[64] Mercedes handed Antonelli his second FP1 outing at the Mexico City Grand Prix, this time in place of Hamilton.

[67] Shortly before the São Paulo Grand Prix, Mercedes announced they would cease development of the W15 due to a lack of available funding following a series of costly accidents since the summer break.

[68] Under the rainy skies, Russell briefly led the race after jumping Norris at the start and held a one second gap.

Mercedes decided to bring him in during a VSC, but an untimely red flag that followed due to Franco Colapinto's costly crash eliminated Russell's advantage.

[74] Russell had a competitive car and made his way to fourth after a contact between Verstappen and Piastri at the opening lap, which he kept near the end of the race.

Hamilton gradually climbed places as the race progressed and had the advantage of the grippier medium tyres since he started with the hard compounds.