In a word, effortless. The 3.0-litre V6 diesel engine endows the A5 Sportback with deep reserves that are easy to access. Despite lacking the outright power of rival units, the engine delivers terrific flexibility at lower revs and a heady punch of mid-range.
Refinement is excellent. The V6 becomes a little vocal above 3500rpm but it is exceptionally well isolated from the cabin, making this car uncannily quiet by diesel standards and, in combination with outstanding longitudinal stability on the motorway, a brilliant long-distance proposition.
Drive is sent through a standard eight-speed automatic gearbox which provides smooth and fast shifts that perfectly complement the nature of the engine. Depending on the driving mode, the torque converter-equipped unit either shifts up early to maximise economy or holds gears for maximum performance. Given the flexibility, you rarely feel inclined to use the steering wheel-mounted paddles, but when you do, the speed of the shifts is impressively rapid, particularly in Sport mode.
The quattro four-wheel drive system apportions power to either end, while an optional sport differential continuously varies the amount of drive to each rear wheel, resulting in superb traction. Grip is good, too, and can be relied on to enter corners at reasonably high speeds and before unleashing the abundant torque at the exit without fear of the car stepping out of line. In all but the tightest corners, it remains terrifically neutral and dependable, both in dry and damp conditions.
As with the A4 saloon sibling, though, the speed-sensitive electro-mechanical steering lacks communication, most notably when turning off centre. There is directness and a sense of weight as lock is applied, but we’d welcome more feel and feedback. In this respect it is neither as fun to drive nor as engaging as the 435d xDrive Gran Coupé.
Nor does this A5 Sportback manage to match the comfort and composure of some rivals. On the optional 19in wheels of our test car, the suspension delivers taut body control and convincing fluidity. The overall ride is more sporting than that of the A4 saloon yet generally sound, with the ability to sponge away small imperfections with little trouble at city speeds. However, it is occasionally caught out by larger transverse ruts and deep potholes at higher speeds.
The combination of a heavy diesel engine and comparatively low-profile tyres contribute to the odd nasty shudder when the road is not perfectly smooth, suggesting the cheaper and lighter 2.0-litre four-cylinder diesel in the forthcoming A5 2.0 TDI, coupled to a and more conservative wheel and tyre choice, might make for a more comfortable car.