Audi RS4 mule 1
Audi‘s all-new, fifth-generation A4 range has only just landed in showrooms, but already we’ve spotted the much racier ‘RS’ version out in the wild. Our exclusive image (below) shows what to expect, and Auto Express can reveal that the existing Audi RS4 Avant, and the subsequent RS5 Coupe, will use a forced-induction V6.
• New Audi A4 review
Following on from the recently-revealed 2016 S4, the RS4 will take that car’s 3.0-litre direct-injection V6 and use new electric turbocharging tech to beef it up to around 480bhp. Both torque and efficiency should be improved greatly over the old, 444bhp 4.2-litre V8.
Audi RS4 mule 2
To the untrained eye this prototype, spotted just outside the Nurburgring, is simply the S4 Avant. It even retains the badging to throw snappers off the scent. But look closer and you’ll spot the extended wheelarches from the RS stable. The fact this is also a load-lugger suggests that again we won’t see an RS4 saloon, but an RS5 coupe is more than likely.
Dr Ulrich Hackenberg, Audi’s head of technical development, explained that a small electric turbocharger can provide instant boost lower down in the rev range as it isn’t driven off exhaust gasses. This then ‘fills in the gap’ until a much larger traditional turbo has spooled up to provide large boost levels for surging top end performance.
The electric turbocharger would be powered by batteries which are charged through a generator that recoups lost energy under braking. This makes it a very efficient system. However, the cost of the components are more expensive than using two traditional sequential twin turbochargers – another method of minimising turbo lag.
2016 Audi RS4 rendering
Dr Hakenberg told us: “This electrical system would only be used on the very top end models.”
That’s why the lesser S4 (which could debut as early as the Frankfurt show in September) will only use a single traditional turbocharger, though Dr Hakenberg said: “This car will still produce in excess of 350bhp”.
He wouldn’t state the exact performance planned for the RS4, set to launch some time in 2016, but did admit it wouldn’t quite match the 503bhp Mercedes C63 AMG S because “that car has eight cylinders”. However, it is likely that Audi will try to keep the same power gap between the current RS4 and the S4, which means the next generation range topper could deliver as much as 480bhp.
The ultimate power output of this engine will also be key to another application: the R8. Dr Hakenberg said: “The R8 is a V10 supercar, there will not be a V8 version again. But there are some markets which demand a smaller capacity engine for that car.”
So it’s likely that once again the R8 will share an engine with the RS4, though this model is only likely to be sold in places such as China, where cars are taxed based on cubic capacity rather than emissions.
Now read our full preview of the 2015 Frankfurt Motor Show.