Each Formula 1 driver gets a fixed allocation of power unit parts for the season, counted separately for the engine, turbocharger, energy store, electrical components and exhaust. Going past the allowance for any one part brings a grid penalty, ten places for the first extra part and five for each one after.
Counting the parts separately is what makes the system complicated to follow. A driver can be comfortably within their allowance on engines and out of them on control electronics, and the penalty applies to the individual component that has run out, not to the power unit as a whole.
For the 2026 season, the first year of the new power unit rules, drivers were allowed four internal combustion engines, four turbochargers, three energy stores, three sets of control electronics, three MGU-K units and four exhaust systems, with one of each treated as a transitional allowance for the new regulations. The limits tighten again from 2027.
Teams therefore plan reliability as a strategic question. Taking a fresh unit deliberately at a circuit where overtaking is easy costs less than taking one where it is impossible, so penalties cluster at particular races rather than falling where the failures happen.