Audi's next M3 fighter rendered

Audi's all-new fifth-generation (B9) A4 sedan and wagon was revealed a week ago, providing an accurate basis for what the replacement for Ingolstadt's cracking RS 4 Avant could look like.

This one comes courtesy of US website TopSpeed, revealing expected modifications including a lower ride height, bigger wheels, beefier RS brakes and a more aggressive bodykit comprising a chunkier grille, front bumpers, side skirts and revised wing mirrors.

However, key questions continue to surround the hottest version of Audi's A4 – and therefore its direct competitor to BMW's M3 and the Mercedes-AMG C 63.

Will Audi continue solely with the RS 4 Avant, or will the new A4 sedan form the basis for a direct rival to the M3 and C 63 sedans? Will the current RS 4 Avant's spine-tingling 4.2-litre V8 continue?

We won't know the answers to these questions until at least late next year, when the RS 4 makes it official debut, following the next-generation S4 sports sedan and the new five-door A5 Sportback and two-door A5 Coupe and Convertible.

The 2016 A5 family will be based on the same new platform as the latest A4, and are expected to emerge within a year of the sedan, perhaps at the 2016 Geneva motor show next March.

That means that while the B9 A4 sedan and wagon should go on sale in Australia in the first half of next year, the first new A5s should follow by end of 2016.

Given recent reports that Audi has ceased production of the current RS 4 Avant and RS 5 Coupe and Convertible, it's possible the new RS 4 could be fast-tracked into production soon.

But given Audi's history of producing a limited number of RS models at once, and the fact it has just launched the upcoming RS 3 hot hatch and is also working on a new TT RS to join the RS 6, RS 7 and RS Q3 (not to mention the new R8 supercar to be launched this week), we don't expect the next RS 4 to top the new A4 range until 2017.

When it does though, it should be a cracker, since it will share the same MLB Evo chassis architecture as the new A4 sedan, which weighs up to 100kg less than the B8, and the new A4 Avant, which is 120kg lighter than before.

Therefore, even with the same engine performance as the current RS 4 Avant, which weighs 1795kg and is powered by Audi's 331kW/430Nm 4.2-litre V8, the new one will offer a superior power to weight ratio.

But word is Audi will ditch the relatively thirsty petrol V8 seen in the current RS 4 and RS 5 for a downsized 3.0-litre supercharged V6, just as the S4 did a generation ago.

The current S4 produces 245kW/440Nm and hits 100km/h in about five seconds, so the new one will need to better those figures, as well as the 5.3-second 0-100km/h sprint Audi is claiming for the new 200kW/600Nm A4 V6 TDI.

And even higher-performance blown V6 should see the next RS 4 comfortably out-pace both the new A4 V6 TDI and next S4, and the old RS 4 (0-100km/h in 4.7 sec).

Logically, however, it will also need to match the likes of the BMW's latest M3, which packs a twin-turbo 317kW/550Nm 3.0-litre straight six to hit 100km/h in a claimed 4.1 seconds and is priced from under $157,000, and the upcoming Mercedes-AMG C 63 S, which arrives this month with a twin-turbo 375kW/700Nm 4.0-litre V8, claimed 0-100km/h pace of four seconds and a $154,900 starting price.

Likewise, the subsequent RS 5 Coupe will need to keep up with the BMW M4 Coupe and Merc-AMG's upcoming C 63 Coupe.