The new Audi RS4 Avant, and the subsequent RS5 Coupe, could have a 3.0-litre V6 engine that uses electric turbocharging technology, Auto Express can reveal. This set up would enable the car to produce big horsepower but with none of the lag associated with high-powered turbocharged cars, plus significantly-reduced CO2 emissions.
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.
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.