With a price nudging £70k even before your pen hovers over the options boxes, it isn’t the cheapest way to experience wind-in-your-hair cruising, but it is one of the most thrilling.
Late last year we tried a left-hand-drive RS5 cabriolet on the continent, but our first test on Britain’s roads came on a sunshine-and-showers spring day that provided ample opportunity to test the automatic roof mechanism.
When the three-layer fabric hood is up, the cabin is well insulated from external noise, even at motorway speeds. With the roof down, wind swirl is low and, naturally, it is the best way to appreciate the car’s full potency.
Unleashing that involves toggling through Drive Select – the system that controls the preset driver modes – to Dynamic. As an aggressive snarl emanates from the oval exhaust tailpipes, acceleration becomes even keener, the steering sharpens and the seven-speed dual-clutch automatic gearbox blurs up through the gears with single-minded intent.
Our test car was also equipped with an optional Dynamic Ride Control system that adjusts the suspension stiffness in tandem with the selected driver mode.
A kerb weight of 1920kg – 205kg more than the RS5 coupé and 15kg more than its main rival, the auto-equipped BMW M3 convertible – gives the engine a fair amount of heft to haul, but it’s hard not to be impressed by the vivacity with which it accelerates from a standstill or serves up mid-range urge.
Slowing down, a task performed by 365mm front and 324mm rear discs, is effective in most situations, although you’re offered the occasional extra reminder of the car’s weight if you have to call on the stoppers in a hurry.
The RS5 cabriolet gets specific spring, damper and anti-roll settings and suspension that’s 20mm lower than the standard A5 cabriolet, and for a big car it feels responsive during cornering. You feel slightly detached from the action, however, possibly as a result of the torque vectoring and trick differential technology that’s redistributing the available power to the wheels and doing some of the hard work on your behalf.
What’s more, the fun of trying to even come close to exploring the limits of the cabrio’s levels of grip and acceleration is spoilt by the over-firm ride, particularly in Dynamic mode. Our test car also rode on 20in wheels (19s are standard), which probably didn’t help the sensation of being jostled uncomfortably from ridge to bump to divot, often accompanied by an unwelcome body shimmy.
Switching to Comfort mode improves the drop-top’s road manners, but is also akin to donning ear-defenders at a Metallica gig: it’s more manageable, but leaves you feeling a step removed from the full-on RS experience.
Drive Select also offers Automatic and Individual settings; the former adapts to the terrain itself while the latter allows elements such as the steering, suspension, engine/gearbox and differential to be set up to the drivers’ preference. It could open the door to a compromise setting that highlights the car's best attributes and reins in the others.