The McLaren P1 will have the combined force of two
highly-efficient powerplants. A mid-mounted 3.8-litre twin-turbo
V8 petrol engine and a highly effective electric motor give a
combined output of 916 hp and a maximum torque figure of 900Nm,
ensuring instantaneous throttle response through the rev range,
more akin to a naturally aspirated engine.

Emissions of less than 200g/km on the combined cycle are reduced
to zero in full electric drive mode, while the Formula 1-derived
DRS and IPAS technologies offer an increase in straight-line
speed and an instant boost of power.
The 3.8-litre twin-turbo V8 petrol engine in the McLaren P1 is a
new version of the familiar M838T unit, that has been
significantly upgraded to optimise cooling and durability under
the higher loads. The engine block has a unique casting to
incorporate the electric motor.
The petrol engine produces 737 hp
at 7,500rpm, and 720Nm of torque from 4,000 rpm.
The lightweight electric motor, developed by the McLaren
Electronics arm of the Group, produces 179 hp, and is unique to
the McLaren P1. The motor produces maximum torque of 260Nm
instantly from a standstill, greatly increasing the throttle
response of the McLaren P1, and peak combined torque of 900Nm is
delivered from just 4,000 rpm.

The electric motor is mounted directly onto the engine, and all
drive is channelled through the dual-clutch seven-speed gearbox
to drive the rear wheels.

Source: McLaren