The McLaren MCL35 is a Formula One car that was designed under the direction of James Key and constructed by McLaren to compete in the Formula One World Championship. The car was originally intended to compete in the season only, but as the championship was heavily disrupted by the COVID-19 pandemic, the lifespan of all 2020 cars was extended into . McLaren produced an upgraded version of the car, the McLaren MCL35M, for the championship as the team returned to using Mercedes engines. Both variants of the car were considered competitive and the team's results improved considerably during the two seasons it was used in, with McLaren regularly the third-fastest team and significantly closer to the leading teams than had been the case since the turbo-hybrid era began in .
The MCL35 represented a substantial development over its predecessor, the MCL34, featuring a new design that increased aerodynamic efficiency and was better optimized for Renault engines. The MCL35 made its début at the 2020 Austrian Grand Prix after the start of the season was delayed by the COVID-19 pandemic. It was driven by Carlos Sainz Jr. and Lando Norris. McLaren finished in third place in the World Constructors' Championship for the first time since and achieved podiums at the Austrian and Italian Grands Prix, while also claiming three fastest laps and setting a track record at the Red Bull Ring.
In 2021, the MCL35M was driven by Norris and Daniel Ricciardo. The updated car made its competitive début at the first race of the season, the 2021 Bahrain Grand Prix, and set two fastest laps, one pole position, and scored five podiums in total. The car took McLaren's first win since 2012 and first one-two finish since at the Italian Grand Prix. McLaren finished fourth in the Constructors' Championship, losing third place to Ferrari.
Competition and development history of the MCL35
Original design and development James Key was recruited from Scuderia Toro Rosso in 2019 to replace the outgoing Tim Goss, and was the MCL35's lead designer. In October 2019 team principal Andreas Seidl stated very little of the MCL34 would be carried over to the MCL35, with the aim of reducing the overall pace deficit to the leading teams which at that point was still over a second. Lando Norris stated that one of the team's major areas of focus was to improve the MCL35's cornering capability.
Compared to the MCL34, the MCL35 design had a greater emphasis on the outwash effect – moving air around the tyre rather than over it – and a higher rear rake. The front wing also had increased outboard loading in order to maximize downforce. The MCL35 featured a thinner nose and a more complex bargeboard, with more space between the front axle and the sidepods to better meet the cooling requirements of the Renault engine. The car utilized a much slimmer sidepod profile, with re-designed brake ducts to increase cooling ability over its predecessor. Key explained that the suspension geometry of the MCL35 had been redesigned to incorporate developments the team had not been able to implement on the MCL34, which included the repositioning of both the upper and lower wishbone elements to influence airflow over the bargeboards and floor.
The success of both the MCL35 and the MCL35M have been in part credited to a change in design process from their predecessors, which emphasised the car as a whole and its performance relative to its competitors rather than the performance of individual components.
Livery
The MCL35 and its livery were originally unveiled in February 2020, featuring the McLaren corporate colour of papaya and blue. Prior to the first race of the season in Austria, McLaren revealed the addition of a rainbow graphic on the sidepod and halo in recognition of Formula One's #WeRaceAsOne campaign. The changes were interpreted by some as representing the LGBT+ rainbow flag, but McLaren stated the rainbow represented their support for diversity in general and provided recognition for essential workers rather than for any specific cause.
In contrast to the MCL34 and its glossy paintwork, the MCL35 was the first McLaren car to be wrapped with vinyl rather than painted, featuring a matte finish and greater use of black in order to lower the weight of the car and reduce the time required to prepare bodywork.
Engine supplier change and preparation for the MCL35M
Aside from minor upgrades, 2020-specification cars were meant to be kept largely unchanged for the 2021 season in order to limit the financial strain on teams that would be incurred by developing a new car under the already fragile financial conditions imposed by the COVID-19 pandemic. Since McLaren had already signed a contract to use Mercedes engines in 2021, they received special permission – subject to FIA inspection – to modify their chassis to accommodate the new engine. This requirement led directly to Formula One's adoption of a token-based system for 2021 vehicle development. Despite switching engine suppliers, McLaren did not switch gearboxes and continued to design and manufacture their own.
Key stated in November 2020 that the planning for the switch had gone smoothly, with the MCL35M to feature "a couple of changes to architecture [made] necessary by the shape of the engine compared to this year's. But it's not fundamentally different." However, Key also stated that the aerodynamic potential of the car could not be maximized due to the FIA's token system, leading McLaren to implement most chassis upgrades and some aerodynamic changes before the switch in the 2020 season. In a post-season statement, Key said that knowing the team would be restricted for development in 2021 "changed our approach when it came to developments this season."
2020 season
Pre-season
Prior to the beginning of the 2020 season, the team publicly established their aim to defend their status as 'best of the rest' – fourth place in the Constructors' Championship behind the then-leading trio of Mercedes, Ferrari and Red Bull – and close the gap to those respective teams. In pre-season testing however, Racing Point, whose car strongly resembled the 2019 Mercedes car, was very quick compared to the other midfield teams and caused McLaren to be less than optimistic about their chances to secure fourth place. Despite this, Sainz said that he was "shocked in a good way" by the MCL35's performance compared to its predecessor, and the team said they were happy with the car's pace. Key would later say that "we didn't really show our pace in winter testing."
After McLaren's withdrawal from the Australian Grand Prix and the race's subsequent cancellation, the season was heavily disrupted by the COVID-19 pandemic and the calendar was reorganized which delayed the car's début for several months. Prior to the opening round, Renault stated that they would not provide any upgrades to the E-Tech 20 engine. Therefore, the MCL35 used the same specification engine for the entire 2020 season.
Opening rounds and double-header events McLaren used a new floor, diffuser, and brake ducts at the Austrian Grand Prix as well as a tweaked front wing. Sainz qualified eighth, while Norris qualified fourth and was promoted to third after a penalty was given to Lewis Hamilton, achieving McLaren's best grid start since the 2016 Austrian Grand Prix. After Norris lost positions in the opening laps to Hamilton and Alex Albon, both McLarens ran comfortably in the top ten for the remainder of the race. In the closing laps, Hamilton collided with Albon and was given a five-second penalty. On the final lap, Norris (then in fifth) overtook Sergio Pérez and set his first fastest lap to finish within five seconds of Hamilton, achieving his first Formula One podium. Sainz finished fifth after also overtaking Pérez. This was McLaren's second podium in three races after the 2019 Brazilian Grand Prix, in contrast to their previous gap of 118 races. The result placed McLaren second in the World Constructors' Championship (WCC) behind Mercedes, with Norris third and Sainz fifth in the World Drivers' Championship (WDC). In an article on strategy calls published in 2021, the team said the result was possible because of the "flawless" double-stacked pit stop allowing Norris to be in position to capitalize on Hamilton's penalty.
McLaren used a new chin spoiler design during the Styrian Grand Prix. Sainz qualified third, the best outright qualifying position for McLaren since . Norris qualified sixth but was demoted to ninth due to a penalty from practice. Norris finished fifth after overtaking both Racing Point drivers on the final lap, while Sainz finished ninth and set the fastest lap and a new track record in the process, a record which still stood when that track format was last used for the 2024 Austrian Grand Prix. Sainz fell to seventh in the WDC.
McLaren used a new engine cover and T-wing design during the Hungarian Grand Prix. Norris qualified eighth and Sainz ninth. Both drivers lost positions changing tyres on lap four, being held up by traffic in the pit lane. Norris finished thirteenth. Sainz finished tenth and was promoted to ninth after Haas driver Kevin Magnussen received a penalty. Norris fell to fourth and Sainz to ninth in the WDC, while the team was overtaken by Red Bull in the WCC.
At the British Grand Prix, McLaren removed the T-wing and reverted their engine cover design to the pre-Hungarian version, while using a new front wing, rear wing, and floor design. Norris and Sainz qualified fifth and seventh respectively, and by the closing laps ran seventh and fourth before a puncture for Sainz dropped him to fourteenth. He was promoted to thirteenth after Alfa Romeo driver Antonio Giovinazzi was penalized, while Norris finished fifth. Sainz fell to tenth in the WDC.
The following week at the 70th Anniversary Grand Prix, Norris qualified tenth and Sainz thirteenth, the latter being the first time a McLaren had failed to reach the final part of qualifying (Q3) in 2020. Sainz later said that the team had discovered an overheating issue in third practice, and in order to be able to complete the race the car had to undergo bodywork changes that compromised his qualifying pace. During the race, Sainz's pitstop was compromised by a wheel gun malfunction. Both drivers referenced tyre management as their main challenge, and Norris and Sainz finished ninth and thirteenth respectively. McLaren was overtaken by two points by Ferrari in the WCC and left the round in fourth place. Norris fell to fifth in the WDC and Sainz fell to eleventh.
Remaining European rounds At the Spanish Grand Prix, Sainz's MCL35 continued to have cooling problems and he was given a new chassis. When this failed to solve the problem, the power unit on his car was replaced; McLaren later stated the issue was unrelated to the chassis. This was the first power unit change for an MCL35 and successfully fixed the issue. Sainz and Norris qualified seventh and eighth respectively, but were concerned about the impact of high temperatures during the race. Despite this, Sainz finished sixth and Norris tenth, meaning they respectively improved to ninth and fell to seventh in the WDC. Having scored 62 points already in the WCC, the team matched their 2018 total in six races.