Like the regular A5, the S5 Sportback will be longer and lighter than today's car, which tips the scales at 2375kg, thanks to weight-saving measures applied from the A4. A switch to five-link suspension is also expected.
While the regular A5 Sportback will share its engine range with the latest A4, the S5 model will use the S4's new 3.0-litre V6 turbocharged petrol motor. In the S4, that engine produces 349bhp and 369lb ft of torque, and similar figures are expected in the S5 Sportback.
The new engine, coupled with the S5's lightweight components and linked to an S tronic automatic transmission, should allow the new S5 Sportback to eclipse the current version's 0-62mph sprint time of 5.4sec. The current S5 Sportback has a supercharged 3.0-litre V6 petrol with 328bhp and 325lb ft of torque.
Like the S4, the S5 Sportback is expected to be available with an optional sports differential. Drivers should also be able to adjust the suspension set-up using Audi's Drive Select system.
As with the current car, the S5 Sportback will receive unique interior fittings, including bespoke seats and badging. Audi's Virtual Cockpit digital instrument cluster will also feature on the options list. Expect quadruple exhaust tips and modified front and rear bumpers to feature on the outside, too.
Prices for the new S5 Sportback are likely to increase over the £42,995 asked for today's car. A public debut could come as soon as the Los Angeles Motor show towards the end of this year.