The Audi RS5 Cabriolet isn't quite as quick as its lighter coupe sibling – 4.9sec 0-100km/h plays 4.5sec – but the roofless variant feels just as fast thanks to the soaring V8 soundtrack that envelops the driver when the top's dropped.
Standard equipment in the Audi RS5 Cabriolet is similar to that in the coupe, which means the powered fabric roof, and the related body and chassis changes, as well as the drop-top specific climate-controlled seats with neck-level heating account for the $20K price premium ($175,900).
The kit list includes 19-inch alloys, xenon headlights with adaptive cornering lights, a multimedia interface-based sat-nav ‘plus’ system, with 20GB hard drive and a pair of SD card slots, Bluetooth with audio streaming, a 180W, 10-speaker audio system, front and rear parking sensors, a rear-view camera, and Audi’s drive select system.
Just as in the coupe, a $4990 optional sports package (as fitted to our test car) brings 20-inch alloys, with a choice of three designs, as well as sports suspension ‘plus’ and a sports exhaust system. Other options include the $2400 variable-ratio dynamic steering system, a $1700 Bang & Olufsen audio upgrade, and a $4900 pair of RS bucket seats (our tip: the powered standard seats are more comfortable).
The Audi RS5 Cabrio marks the Australian debut of the brand’s Audi Connect system. The $800 option allows occupants to use a range of handy online services via the car’s multimedia interface and acts as a wifi hotspot for mobile devices.
Only BMW will offer a true rival for the RS5 cabrio when the folding-hardtop M4 arrives. The 316kW rear-wheel-drive convertible will almost certainly be the more focussed performer of the pair, though the twin-turbo six-cylinder BMW may not have the V8 Audi’s aural appeal.
Mercedes’ A5 rival, the C-Class Coupe, isn’t offered as a convertible, which leaves the maker’s E-Class cabrio in the frame. There’s no AMG version, but the flagship, $140K E400, with its twin-turbocharged V6, could fit the bill as a less-expensive alternative.
However, the most serious drivers will pocket $45K and slide into the $130K, 232kW rear-drive Porsche Boxster S, which is just as quick in a straight line as the Audi, though like the Jag it’s a two-seater and more in the realm of roofless sports car.
Audi chose a lightweight textile roof for the RS5, rather than the increasingly common folding hardtop, and worked tirelessly to reduce interior noise levels. With the top open at urban speeds the wind-blocker makes the cabin a quiet and comfortable place. When the roof powers shut, an impressive level of calm comes over the cabin – thank the 15mm-thick acoustic foam lining.
It takes 15 seconds to drop and 17 seconds to raise the top, and can be done while driving at speeds of up to 50km/h. When stowed, the folded roof mechanism eats up 60 litres of the available 380 litres of boot space. The rear seats fold via a boot lever liberating a total cargo capacity of 750 litres.
Chassis reinforcements that come as part of the transformation from coupe to cabrio add more than 200kg. A pair of aluminium front guards help, but the drop-top RS5 remains dangerously close to the double-ton, at 1920kg. However, our drive on notoriously bumpy roads in the NSW Hunter region suggests the body can’t cope with the RS-spec suspension – the whole windscreen can be seen shaking and the steering wheel wobbles disconcertingly.
In an era of downsized turbo engines, Audi’s 4163cc all-aluminium non-turbo V8 is a beacon of hope. The engine produces its 331kW at a high 8250rpm and is big on character and, when the flaps of the optional sports exhaust are wide open, volume, too. Meanwhile, the 430Nm slug of torque that hits you between the shoulder blades between 4000 and 6000rpm delivers the 4.2-litre point home convincingly.
Audi’s S-tronic seven-speed dual-clutch proves a fine partner to the V8 in most driving, thanks to its rapid-fire upshifts and sharp responses to paddle shifts, though ‘sport’ mode locks out seventh gear and puts the transmission a ratio or two low for anything other than hard driving. In comfort, upshifts are intuitive but there’s often a frustrating delay during kick-down as the ’box sorts out a lower ratio.
Combined cycle fuel-consumption of 10.7L/100km is reasonable considering the RS5 cabrio’s weight and the performance underfoot.
The quattro all-wheel-drive system is perhaps the RS5 cabrio’s biggest ace over rear-drive rivals. The tenacious traction available allows the two-door to slingshot out of corners.
The Audi’s torque vectoring system is based around a crown-gear centre diff, which can differ from its usual 40:60 torque split, sending up to 70 per cent of torque to the front, or 85 per cent to the rear. Giving it more throttle isn’t an intuitive mid-corner response to the onset of understeer but, with help from the rear sport diff, actually helps point the RS5’s nose around the corner. These clever drive systems pair perfectly with the paddle-shifted dual clutch to make the driver feel like a gun. Being quick from point to point is easy, just as long as the road is smooth…
With Audi’s optional dynamic ride control fitted there’s more covert cleverness at work. Diagonal shock absorbers are connected via hydraulic lines, providing an anti-roll function. It’s effective on long sweepers, though the system lacks polish during quick changes of direction.
On fresh urban blacktop both the comfort suspension mode and the noticeably more tied-down sport feel well judged, but on ripply or patched-up backroads neither delivers the expected level of comfort.
The RS5 cabrio’s steering is accurate enough, though not great at delivering feel to the fingertips. Dialling up Sport adds weight, but we found the Comfort setting felt more natural. An Individual mode lets the driver tailor a setting to suit. We found Dynamic differential and exhaust modes, but Comfort for the steering, suspension and drivetrain the best combo, though on an undulating road with a smooth surface, sport suspension would bring better body control with little ride penalty.
The Audi RS5 Cabriolet has the high-performance, four-seater soft-top segment all to itself, but that doesn’t make it the automatic choice. If you can sacrifice the rear seats, there are alternatives that bring greater driver involvement and don’t suffer the Audi’s scuttle shake and poor rough-road ride quality. Or, if not, there are Mercedes’ E400 and BMW’s forthcoming M4 Convertible to consider. Meanwhile, if you can do without the drop-top, the re-priced $155,900 coupe is the pick of the RS5s.