The S5 was launched as a coupe with a 4.2-litre V8 FSI engine delivering 354bhp and immense low down pulling power. It sounds superb, with a deep rumble on start-up and a loud howl when accelerating while a 0-62mph time of 5.1 seconds ensures it's no slouch. The V8 certainly has plenty of character and although it may not always provide a sudden burst of acceleration, it manages to build speed effortlessly.
The standard gearbox is a slick six-speed close-ratio manual while there's an optional six-speed tiptronic automatic. This gives super-swift and smooth changes and there's also a manual mode, allowing you to change gears using steering-wheel mounted paddles. However, while it's impressive, it robs the driver in terms of enjoyment and involvement. The convertible version, launched in June 2009, actually uses a totally different engine.
It's a 3.0-litre TFSI fitted with a supercharger that boasts 333bhp and a 0-62mph time of 5.6 seconds. It's considerably more economical than the coupe, averaging 29mpg compared to just 23mpg in the hard top version. This version gets a seven-speed S tronic gearbox as standard - the semi-automatic system uses two clutches to provide lightning fast shifts and works extremely well in the S5, helping it build speed effortlessly.
It's sedate and smooth at lower speeds but still sounds good under hard acceleration with each gear change accompanied by a brief roar.
Both models come with quattro all-wheel drive, which means the S5 is able to put all that power down without spinning its wheels. It also results in excellent traction, even in the wet, along with extra confidence when accelerating out of corners or roundabouts. The steering has plenty of weight and is responsive too, but like the standard A5 it does lack a little in feel.
Compared to its most obvious alternatives - the BMW 3-Series Coupe and Convertible - it doesn't offer the same amount of feedback to the driver. It's great in bends though with minimal body roll and feels poised and composed, even when pushed hard. As a result, it's an ideal grand tourer that's effortless and enjoyable to drive.