Honda returned to Formula One as an engine supplier in 2015 for the second season of the V6 turbo-hybrid regulations, reviving their relationship with 1980s and 1990s partner McLaren. Honda's power unit was designed around McLaren's very tight chassis design and aerodynamic requirements, which they had dubbed their "size zero" philosophy. Over the 2015 season, the McLaren-Honda package proved to be significantly underpowered and unreliable, and the team finished ninth the constructors' championship with fifth place in Hungary as their best result. Reasons for the lacklustre performance included Honda lacking experience and data with the new regulations, a token system limiting development, as well as fundamental issues with McLaren's "size zero" chassis concept. McLaren had also persuaded Honda to return a year earlier than initially planned.