These are the first official pictures of the all-new Porsche 911.

Known internally as the 991, the new 911 — the sixth truly independent model in an illustrious 48-year history — is set to make its world debut at next month’s Frankfurt motor.

The new 911 will initially be sold in rear-wheel drive Carrera and Carrera S coupé guises. Cabriolet and four-wheel-drive variants will follow in 2012, and pave the way for a range-topping Turbo packing 523bhp in 2013.

Developed under Porsche design boss Michael Mauer, the visual changes are subtle but effective enough to set the new car apart from its predecessor.

The traditional round headlamps are set on the front of a wider, slightly higher front bumper. The lights have been made bigger and house more complex internal graphics than before, and are complemented by new LED daytime running lamps on the leading edge of a reshaped bumper. The rear is distinguished by new, thin LED tail-lamps. They sit underneath a prominent lip that forms the trailing edge of the engine lid and wrap further around the rear bumpers than before.

As with the outgoing 911, the new model has a choice of two standard naturally aspirated, horizontally opposed six-cylinder engines mounted aft of the rear axle line.

The big news concerns the downsizing of the base unit in the Carrera. It drops in capacity from 3.6 litres to 3.4 litres — the same as the Boxster S and Cayman S. But while the Boxster/Cayman S engine delivers 316bhp, the new Carrera packs a sturdier 345bhp at 6400rpm — up by 4bhp over the old 3.6-litre engine. It also has 280lb ft of torque.

The Carrera S continues with a 3.8-litre unit, but it has changes to the induction and exhaust which liberate an extra 14bhp at 394bhp at 7000rpm and this version boasts 324lb ft. At the rear, the Carrera continues to feature two oval exhaust pipes, while the Carrera S gets four round pipes.

The new model receives a new seven-speed manual gearbox — a first for a series production road car.

There have been significant chassis changes as a result of the lengthened wheelbase in the quest to further improve the handling, grip and ride.

Expect the new 911 to reach our shores soon after the global launch.