What the sporting regulations say:
- Unless he drives for more than one team, each driver may use no more than five power units during a championship season. The only exception is where the power unit is provided by a manufacturer or supplier taking part in its first championship season, in which case up to five may be used by a driver.
- The power unit is deemed to consist of six separate elements: the internal combustion engine (ICE), the motor generator unit-kinetic (MGU-K), the motor generator unit-heat (MGU-H), the energy store (ES), turbocharger (TC) and control electronics (CE).
- Each driver is permitted to use only five of each of the above six elements during a championship season and any combination of them may be fitted to a car at any one time. Should a driver use more than five of any of the six power unit elements during the course of a season, a grid penalty will be imposed.
- The penalties imposed for using additional elements work thus: the first time a sixth of any of the elements is used, a ten-place grid penalty will be imposed. A five-place grid penalty will then be imposed the first time a sixth of any of the remaining elements is used. Likewise, the first time a seventh of any of the elements is used, a ten-place grid penalty will be imposed, and so on.
- If a driver is replaced at any time during the season his replacement will be deemed to be the original driver for the purposes of assessing power unit usage.
What the technical regulations say:
- The internal combustion engine of a Formula One car must 1.6-litres in capacity and rev-limited to 15,000rpm.
- The engine must also have six cylinders arranged in a 90-degree formation, with two inlet and two exhaust valves per cylinder and a single turbocharger.
- Engines exhaust systems must have a single tailpipe for the turbine and either one or two tailpipes for the wastegate.
- Fuel flow to the engine is limited to 100 kilograms/hour.
- The use of any device, other than the engine and one MGU-K, to propel the car, is not permitted.
- The overall weight of the power unit must be a minimum of 145kg. The Energy Store must be installed wholly within the survival cell and must weigh between 20kg and 25kg.
- The crankcase and cylinder block of the engine must be made of cast or wrought aluminium alloys - the use of composite materials is not allowed. The crankshaft and camshafts must be made from an iron-based alloy, pistons from an aluminium alloy and valves from alloys based on iron, nickel, cobalt or titanium.
- The MGU-H must be solely mechanically linked to the exhaust turbine of the pressure charging system. The MGU-K must be solely and permanently mechanically linked to the powertrain before the main clutch.
- A maximum of 4MJ per lap can be transferred from the ES to the MGU-K (and then in turn to the drivetrain).
- A maximum of 2MJ per lap can be transferred from the MGU-K to the ES.
- An unlimited amount of energy can be transferred between the MGU-H and the ES and/or MGU-K.
- With the exception of cars starting a race from the pit lane, the MGU-K may only be used during a race start once the car has reached 100km/h.
- Each power unit manufacturer is allocated 32 development tokens during the course of the season which they can spend as they choose in order to make modifications. New power unit manufacturers are allocated 15 tokens in their first year and 32 in their second.