[14] Reliability however was improved from the previous year, and the team greatly benefitted from their rivals' problems to score points from the early races.

[9][10] During negotiations to secure a new supplier, Renault disclosed that they did not have the capacity to supply McLaren whilst meeting their commitments to customer teams Red Bull Racing and Scuderia Toro Rosso.

[23] The decision to change from Honda to Renault engines brought with it several challenges for the design team led by McLaren technical director Tim Goss.

The team were subsequently required to redesign the gearbox and completely overhaul the rear suspension mounting points in order to fit the engine.

The design combined all of the upper elements of the suspension into a single piece, thus minimising the amount of bodywork in a key area of the chassis and in turn reducing drag whilst giving the team a greater degree of control over air flowing over the rear diffuser and producing more aerodynamic grip.

The team introduced a temporary cooling package for the duration of the test ahead of a planned update to the car's bodywork,[26] and later expressed confidence that the engine reliability issues had been resolved.

Teams reported that the reinforced chassis needed to withstand the equivalent weight of a London bus in order to pass the mandatory crash tests.

[29] The "shark fin", a carbon fibre panel extending backwards from the engine cowling was removed after McLaren lobbied to the FIA to have it written out of the technical regulations.

[31] Prior to the car's launch, McLaren announced plans for an extensive aerodynamic update to be introduced for the opening round of the championship in Australia.

[32] However, the team later admitted that their reliability issues during pre-season testing had forced them to delay the introduction of planned upgrades until the second round in Bahrain.

[33][34] The updates featured revisions to the front wing that were aimed at stabilising the airflow over the car and a new design for the bargeboards and turning vanes that was modelled on a concept pioneered by Red Bull Racing and Ferrari in 2017.

[38] Commentators noted that the upgrade package integrated concepts originally developed for the Red Bull Racing RB14, Sauber C37 and Force India VJM11.

[55] Alonso and Vandoorne qualified in thirteenth and fourteenth once more in China,[56] as the team struggled with excess drag, particularly on the circuit's long back straight.

[58] Alonso was involved in a first-lap incident with Hülkenberg and Sergey Sirotkin that saw his car heavily damaged but went on to finish seventh in a race of attrition.

Vandoorne struggled with tyre temperatures in the cool conditions, making several pit stops under the safety car to finish ninth.

He qualified fourteenth but was forced to start from pit lane after the team broke parc fermé rules to replace his front wing.