Making a fast car out of a convertible is as easy as stuffing a big engine into it. Making a good fast car out of a convertible isn't as straightforward. By putting the evocative S badge on this A5 Cabriolet, Audi is basically saying that this is a proper sporty car - fun to drive as well as being quick. The problem is, the base car, the A5, isn't known for its dynamic prowess. So, does the S5 Cabriolet live up to its badge?
What are its rivals?
You don't need to venture away from Germany to find this car's chief rivals - actually, you rarely do with any German car. Funnily enough, both BMW and Mercedes have cabriolets that are very close to this in terms of price, performance and practicality. There's one key difference though: this is the only one with legitimate high performance branding.
The BMW 335i M Sport Convertible is a big engined version of the 320d M Sport Convertible, and the same principle can be applied to the Mercedes E350 CGI Sport Cabriolet. Shrewd marketing on Audi's part, perhaps, but true all the same. Plus, at £45,150, the S5 is the cheapest by a few hundred pounds.
How does it drive?
Audi offers a Drive Select package for all its quick stuff now, whose purpose is to allow customisation of the driving experience through a few levels, from comfort to sporty. It lets you tinker with the throttle feel, gear change aggressiveness, steering weight and suspension firmness. Does it work? In this case, yes.
What you get is a car that's always on the firm side, and always feels big, but which can at a stroke (of a button) go from being quiet and comfy, to quite loud and entertaining. It's never a pure driving experience, in the sense that the best driver's cars are, but it always feels like you're piloting an engineering achievement.
That's because, in Sport mode at least, the steering is pointy and heavy, the gear changes of the seven-speed twin-clutch automatic outrageously quick, and the throttle response instant. To top it off, the very clever Sports Differential, which basically sends more power to the back wheels than the front, makes it behave more like a rear-wheel drive car at times. So, it's got masses of comforting four-wheel drive quattro grip, yet through corners feels like it's being pushed form the back wheels - like a BMW.
Two things stand out after spending a bit of time with an S5: the engine and the roof. The engine because it's so powerful, so flexible, from anywhere in the rev range, and the roof because it's so good at keeping wind and road noise out. Better, we think, than a lot of folding hard top convertibles, but of course with the added advantage of folding away quite compactly, leaving a big boot. It's optional, but it should be the first option you tick.
The engine, a 2.0-litre supercharged TFSI unit with 328bhp, is an absolute gem. In fact, we like it more than the much more powerful V8 engine in the RS5. It's the combination of its low rev grunt and high-end urgency that makes it feel quick all the time. It's also capable of 29.1mpg - a realistic figure, we've found, if you can drive with subtlety.
We're open to disagreement on this, but for us the S5 could do with a little more performance excess. The silver mirrors, quad tailpipes and S5 embossed leather sports chairs are nice, but really, from most angles this could be an S-Line diesel convertible.
The gearbox is also more suited to speedy driving than normal, everyday stuff, because it tends to jerk the car forwards when doing low speed down shifts. It's not a massive deal, but a noticeable issue.
Should I buy one?
If you're in the market for a fast and flexible (in the practicality sense) four-seat convertible, this one is very easy to justify. Whether it's that much better than a 3.0-litre TDI A5 though - which is cheaper to buy, tax and fuel - is debatable. Still, it's one of the most complete convertibles you could want, with useable back seats, a big boot, reasonable economy (given the pace), pleasant looks, and the usual Audi build quality. Impressive indeed.