Leaked: McLaren 688HS caught again

McLaren's top-secret 688HS (High Sport) has once again been leaked online after a single image of the car being built at the car-maker's Woking HQ appeared on a fan site for the British supercar maker.

Showing an aggressive new aero package that includes four new carbon-fibre canards (wings), front-wheel-arch air extractors and a centrally-mounted roof air intake the latest version based on the current 675LT is believed to be the work of McLaren Special Operations (MSO).

Commissioned by a wealthy owner, the new 688HS is thought to be a one-off and will not be offered as a full production model.

Adopting its name from the 688hp (506kW) the modified twin-turbo 3.8-litre V8 generates 9kW more than the standard 675LT but its performance gains from it weighing in less than the  standard car.

Engineers have shaved between 40-50kg from the regular 675LT's kerbweight, it’s claimed.

Factor in more torque from the twin-turbo V8 and the 688HS is almost certain to better the 2.9 seconds it takes for the current 675LT to reach 100km/h.

Top speed, meanwhile, might actually be less than the 675LT's 325km/h - but only because engineers have worked hard to maximise downforce.

Not pictured is what’s claimed to be a completely reworked huge rear spoiler and heavily modified rear diffuser.

Created to be the ultimate track day tool, the 688HS also benefits from the aero design and handling know-how lifted from the works-650S GT3 race car that competed — and won — this year’s Bathurst 12 Hour.

It’s not known how much the 688HS has cost, but it's rumoured its wealthy owner spent more than $2 million dollars commissioning it - almost four times the $620,000 McLaren charged for the sold-out 675LT Spider.