TOP-DOWN motoring just became a little more alluring in Australia with the arrival – just in time for summer – of the 313km/h cabriolet version of Audi’s R8 mid-engined supercar, the R8 Spyder.

The snarling German glamourpuss sets a new high-price watermark for the Audi range in Australia at $392,000 for the automatic version – $28,600 more than the previous range-topper, the V10-powered R8 Coupe on which it is based.

The new sports flagship hits the Audi showrooms next month, along with another Audi tour de force, the 331kW V8 RS5 quattro super coupe that was also launched today at Phillip Island.

Twelve months in the pipeline since it was unveiled at the 2009 Frankfurt motor show, the two-seat R8 Spyder undercuts equivalent models in Mercedes-Benz’s SL range, which tops out at $508,500 for the SL 65 AMG, and Porsche’s range-topping 911 Turbo S Cabrio ($442,800).

The R8 Spyder is also more than $100,000 dearer than the most affordable Audi R8, the V8-powered R8 4.2 FSI.

Unlike the R8 Coupe, which comes with a choice of 4.2-litre V8 or 5.2-litre V10 FSI engines, the Spyder will launch with only the bigger engine that is sourced from Volkswagen stable-mate, Lamborghini.

Generating the same 386kW of power at 8000rpm and 530Nm of torque at 6500rpm, this engine cranks the aluminium and carbon-fibre 1720kg sports car from standstill to 100km/h in 4.1 seconds – 0.2s slower than the slightly lighter R8 V10 coupe.

Top speed is said to be 313km/h – again slightly slower than the coupe.

The six-speed manual transmission-equipped Spyder tips the price scales at $376,100, while the R Tronic six-speed sequential automated gearbox variant – offering normal, sport and manual shift modes – is an extra $14,000, at $392,000.

Combined fuel economy is said to be 13.9 litres per 100km – 0.2L/100km thirstier than the R8 Coupe.

While the aluminium space-frame body has been strengthened to account for the loss of the roof, Audi said the Spyder's aluminium and carbon-fibre body weighs just 216kg – a mere 6kg more than the coupe.

As well, Audi chose a lightweight fabric roof instead of a folding metal top for the Spyder, containing the weight of the top to 46kg.

Powered by an electro-hydraulic motor, the roof is said to open or close in just 19 seconds, and can be done while driving at up to 50km/h.

Interestingly, the heated glass rear window can be raised or lowered independently with the touch of a button. This flat glass panel slides vertically out of the rear bulkhead, locking into a slot in the soft-top's frame when the roof is raised, and can even be left partly raised to act as a wind-blocker if the driver wishes.

A removeable wind deflector can be installed separately.

Audi said the Spyder’s body shares about 70 per cent of parts with the Coupe, but among the modifications are thicker A- and B-pillars, heavier side sills, the addition of an underfloor cross-beam and strengthening plates and additional sections in the doors.

The roof storage compartment cover is fashioned from carbon-fibre, while the engine cover and rear spoiler are of fibre-reinforced plastic.

The rear spoiler has been reshaped for the Spyder, and extends automatically at 100km/h or at any other time at the push of a button.

Like the spoiler of the coupe, the unit has mesh inserts that help to vent hot air from the engine when lowered into its rear recess.

Gone of the R8 Coupe's glass engine cover that allows proud owners and envious bypassers alike to gaze in on the big V10, replaced by a new engine-cum-roof cover with double lines of distinctive silver-painted vents.

This cover lifts away electrically to allow the soft-top - stored above the engine on an insulated compartment - to unfold.

Also unique to the Spyder are vertical air intakes in the flanks and new trim strips on the doors. The signature carbon-fibre side 'blades' of the coupe are also gone for model.

Roll-over protection is provided by two spring-loaded alloy plates that shoot up from the rear bulkhead in 0.2s once a seat-belt pretensioner or airbag deploys.

Like all high-performance Audis, including the R8 Coupe, the R8 Spyder puts power to the tarmac via the company’s trademark quattro all-wheel drive system.

A viscous coupling diff distributes power between the axles, with about 85 per cent typically going to the rear, where a locking rear differential further improves traction.

As well, the R8 has launch control for super-slick starts, even on the manual models.

Forged aluminium triangular wishbones locate the wheels at all four corners, where braking is provided by big ventilated discs – 365mm at the front and 356mm at the rear – gripped by eight-piston callipers at the front and four-piston types at the rear. Ceramic discs are a $25,422 option.

The R8 Spyder rides on continuously variable magnetic dampers – HSV and Ferrari-style – helping to improve both the ride comfort and handling of the car.

The R8 has 19-inch forged alloy wheels – 235 wide at the front and even fatter 295 at the rear.

Like the R8 Coupe, the Spyder employs Audi’s world-first LED headlights – both high and low beams – as well as LED running lights and turn signals. These lights are said to use less energy, last longer and look cool.

The rear bulkhead has a storage compartment with three bins stacked vertically between the seats, while the under-bonnet luggage area holds 100 litres of baggage.

Most of the interior is clothed in black leather, with contrasting red rings around the instruments, a solid aluminium gear knob and alloy-look pedals. LED lighting gives the interior a soft glow, if you wish.

The power-adjustable leather-clad sports seats are heated and can be trimmed in five alternative colours if black is not to your taste, and are specially treated with a pigment that is said to cut heat build-up from the sun.

Standard equipment includes sat-nav, a driver information system with lap timer, 465-watt Bang & Olufsen sound system and climate control air-conditioning.

An optional seat-belt-mounted phone microphone system is said to allow calls at highway speeds with the top down. With the lined soft-top up, cabin noise levels are claimed to be similar to the Coupe at 120km/h.