McLaren’s P1 supercar will be a 903-hp plug-in hybrid

By the time we actually see the McLaren P1 in the carbon fiber next week, there won't be many details left not already announced by the British supercar maker. Today, McLaren leaked out the power and engine specs of its new supercar, announcing the P1 would offer 903 hp thanks to a combination of a twin-turbo 3.8-liter V-8 and a massive battery pack that can be charged from the outside — making it the world's fastest plug-in hybrid.

McLaren says the 3.8 liter V-8 will churn out 787 hp on its own, while the electric motor and battery pack add an additional 176 hp, all of which routes through the 7-speed dual-clutch transmission to the rear wheels. The battery pack, which adds a surprisingly small 211 lbs of weight to the P1, allows the car to drive 6 miles on electricity alone — and if depleted, can be charged from an outlet. To make the connection with its Formula 1 machines, McLaren says the P1 will come with an F1-like electric boost dubbed the Instant Power Assist System, a button on the steering wheel that commands the electric motor to provide all of its power instantly.

All this in a car that McLaren suggests could get about 25 mpg in everyday driving. Which is the real point of all this electric technology: McLaren and other supercar makers aren't immune from tough fuel economy rules in Europe, the United States and Asia, and adding a dash of green-ish technology appeals to the billionaires who can afford the P1, the upcoming Ferrari Enzo successor and Porsche's hybrid 918. As the P1 shows, top speeds alone are no longer sufficient to make a supercar super.

UPDATE: Here's a new spy video catching the P1's engine sound during McLaren's test drives: