Are you sitting down comfortably, Internet? Presumably you’re aware that McLaren is currently building a super-super car called the P1. And you’ll be privy to some cursory information such as a) it’s a car, b) it’s got wheels, and c) it’ll be pretty fast.

Well, pretty ruddy fast, actually. Because today, McLaren has announced that the powertrain fitted into the middle of the P1 develops 903bhp. Nine hundred and three.

See NEW pics of the McLaren P1 including its engine

Got your breath back? First, it gets a version of the 3.8-litre twin-turbo V8 from the MP4-12C, which has been heavily modified for cooling and durability. As we’ve mentioned before, McLaren has been working closely with Mobil 1 on fluids for this V8; a V8 that includes a special casting to incorporate an electric motor.

On its own, the petrol engine develops 727bhp at 7,500rpm and 530lb ft of torque from 4,000rpm. The electric motor that sits underneath has been developed by McLaren’s ‘Electronics’ division, and it adds another 176bhp and 191lb ft of torque… instantly. As in, from zero rpm. McLaren tells us the combined torque comes rushing towards your intestines at 4,000rpm.

In addition, there’s something called an “Instant Power Assist System” (IPAS) that offers up the electric motor’s 176bhp instantly as a ‘boost’ function, which McLaren reckons “provides a sharper throttle response more associated with a normally aspirated engine”. This motor also acts to help gearshifts on the seven-speed dual-clutch box: it applies “instant negative torque at the point of shift”, which apparently drops the engine revs quickly to the required engine speed. Yeah, us neither, but it sounds ace.

As expected from a hybrid, you can run on the 3.8-litre V8, the electric motor, or both. Run just the electric motor and you’ll achieve a gold star for emissions (zero), and will be able to travel just over six miles (10km) before the 96kg battery pack - mounted onto the underbody of the carbon fibre chassis just behind the passenger cell, and thus better for weight distribution - is drained. And this being McLaren, even the battery gets complex cooling systems: the coolant flow is balanced so that each individual cell in the entire pack is cooled to the exact same temperature.

You can recharge the battery from a plug socket in just two hours, but range anxiety is clearly not a worry here; once empty, the twin-turbo V8 immediately fires into life to remind you that sometimes, the future doesn’t need to come so quickly. Even so, McLaren claims just 200g/km of CO2 (admittedly on the combined cycle) for the new P1.

Oh, and remember when Formula One first introduced the Drag Reduction System a couple of years ago, and you all sat there at home thinking, ‘I need one of those in my life’? Well, the P1 gets DRS through a moveable flap on that lovely rear wing, reducing drag by 23 per cent. What this basically means is a higher top speed. Geneva can’t come soon enough, right?