There is an article in this week's Autocar Magazine on the new RS4. It shows the black mule we've already seen that may or may not be an RS4 prototype lapping the Nordschliefe.
It confirms what I think we can now regard as fact: the engine is an extremely exotic development of the current 4.2 litre V-8 engine as used in the S4, A6 and A8 models. THERE ARE ABSOLUTELY NO TURBOS - but don't worry because the naturally aspirated development they intend to put in it will punch harder than Lennox Lewis on steroids and has quite a few trick bits that really lift its game. Moreover, it revs well beyond 8,000 rpm to deliver a healthy 425 bhp. Performance is above and beyond both existing RS4 and RS6 models, with 0-100 kph achieved in under 4.9 seconds and a top speed limited to 250 kph. Apparently, quite a few kilogrammes have been shed but it still weighs in at a flabby 1600 kg. The article reports that a 6-speed manual box will be offered as standard with the option of DSG box, although the latter seems to be speculation rather than fact.
I spoke to someone at Audi about this article and can tell you that it only tells half the story. What you need to know is that the new RS4 is not merely designed to blitz the BMW M3 or Mercedes-Benz C55; it's true target is the new M5. This is the reason why they've chosen a high-revving naturally aspirated engine. It's a development of the existing 4.2 engine because this is a proven motor and therefore a much more reliable start-point for tweaking.
By contrast, the new engine in the BMW M5 has not yet been perfected. Even though the car has been announced, its release may actually be delayed because they are having all kinds of problem with reliability - there is talk of engines detonating and so on. Of course, they'll get it right, but my sources tell me that it is far from production ready as things stand.
The new RS4 will be Audi's top-of-the-line sports car until the new RS6 arrives and therefore the engineers are doing everything possible to make it absolutely fantastic - including hiring some of BMW's best engineers to complement Audi's own home.
You may remember another recent article that reported Audi believes there are better ways to deliver performance than a sheer horsepower battle. This car should prove that. Let's hope so.