From 2017, new F1 regulations demanded major transformations in chassis design. To increase speed and enhance the looks, 2000 mm wide bodies were back for the first time in 20 years since 1988, when the maximum width was reduced to 1800 mm to suppress top speed. Front wing width was increased from 1650 mm to 1800 mm, and tire widths were increased from 245 mm to 305 mm at the front and 325 mm to 405 mm at the rear, resulting in larger F1 cars.

This was a year of great change at McLaren. After the previous season, Ron Dennis, who had led the McLaren Group, was dismissed, and racing director Eric Boullier assumed leadership of F1 activities. With the change of organization, “MP4,” which had been used for a long time under Dennis, was changed to “MCL,” and the base color of the car was changed to the orange used when the team was first established.

The MCL32, introduced to meet the new regulations, retained the short nose and front wing configuration of the MP4-31, and was characterized by bargeboards with an ingenious airflow from the front wing to the rear. The input from the tires as well as increased grip gained by the wider tires was unknown, and the amount of tolerance depended on the teams’ judgement. A larger margin would result in an increase in weight, and there was still insufficient data to find the optimum value. McLaren, with its abundant resources, used highly accurate simulation technology to optimize the suspension and strength of each component, and also developed aerodynamic measures such as bargeboards and rear wings. McLaren joined other teams in adopting the “T-wing,” considered a loophole in the first year of the regulation changes. The small wing attached to the rear end of the engine cowl did not generate a large amount of downforce, but was highly regarded as being effective, and had been tried in several grands prix with different shapes and number of wings.

In 2017, Honda introduced the RA617H, a power unit with completely different specifications from the previous RA615H and RA616H units. The company had determined that although it achieved a certain level of reliability, the RA617H needed to match its competitors in terms of power by improving the efficiency and high-level control of each part of the engine, starting with the combustion system. Development of the new power unit had been underway since the previous year, and was used from the pre-season tests of the 2017 season. A major feature of the new engine was that its turbine and compressor, which had been housed between the V-banks, were moved outside of the engine, allowing the driveshaft to be lowered, significantly lowering the center of gravity. Technology to rapidly ignite the fuel-air in the main chamber by forcing it through a small hole from the pre-chamber covering the spark-plugs’ electrodes was also adopted. Honda took on the challenge to create a power unit that could deliver performance matching the best, but a big pitfall awaited when the car was actually driven.

From the beginning of testing, Honda’s new power unit was plagued with problems and low output. First, oil would not flow sufficiently due to the shape of the oil tank, severely hampering performance. The first test ended without much testing of the chassis. In the second test, to prioritize chassis testing, power output was reduced to avoid problems, but lap times were sluggish. The tests had driven a wedge between the team and Honda. Honda did its best to restore reliability, but once the season started, the power unit lacked power and the MGU-H developed issues. The shaft had been lengthened due to a change in the MGU-H’s positioning, resulting in uncontrollable torsional vibration that made the car hard to drive. The MGU-K also had issues due to the drive gear train being moved from the rear to the front, causing resonance.

As the season began, race results were more sluggish than ever before. Problems continued, and points only came in Round 8, Azerbaijan, and in Round 11, Hungary where both cars finished within the points for the first time. It was, however, too little too late.

McLaren decided to terminate the contract with Honda, and the partnership with Honda was set to end once the 2017 season was over. Having lost its power unit customer, Honda was forced to choose between ending its activities, or finding a new partner. Franz Tost, the head of Toro Rosso, came to the rescue of Honda, which had no significant track record. At Round 14 in Singapore, Honda officially announced that it would supply power units to Toro Rosso, Red Bull’s sister team, from 2018. Honda’s F1 activities were about to move into a new stage.