It's not often you get to put a top-secret prototype through its paces. But's that's exactly what Cosworth has let Auto Express do. The Northants-based engine specialist has let us loose in this super saloon that makes BMW's M3 seem like a milkfloat. The car is the running prototype for the forthcoming Audi S4 V8 and now we can bring you a world exclusive preview of it.
>With turbocharging falling out of favour, Audi has realised there's no substitute for cubic inches. So rather than develop the twin-turbo V6 in the current S4 and RS4, the next-generation S4 will use a V8. To give a hint at the potential of putting a big engine in a compact car, the German company's British off-shoot, Cosworth Technology, took an ordinary S4, removed its V6 unit and shoe-horned in a 360bhp 4.2-litre V8 from the S8. This project involved re-engineering the S4's subframe, employing twin exhaust pipes and giving it a massive radiator to cool the new engine.
Squeezing that mammoth aluminium unit into a standard S4 engine bay was almost impossible and the central snout, headlights and bonnet all had to be modified. To complete the look, a grille from the TT was added. Although the V8 powerplant is only 20kg heavier than the iron block six-cylinder from the S4, the suspension had to be modified with uprated front springs and a 20mm lower ride height. Huge 18-inch alloys set off the sportier look.
Cosworth Technology's engineers wanted the V8 Audi to resemble a factory car as much as possible and, although they only had two days to modify the driveability of the new machine, they did a fair job.
As this is an Audi, it comes with quattro four-wheel drive - and with the 4.2-litre lump under the bonnet, it needs it. Turn the key and the engine whispers into life; floor the throttle and there's scarcely time to change into second gear before the 5.1-second charge to 60mph is completed. In 13.2 seconds from standstill you could hit 100mph and, should you have a test track at your disposal, the Cosworth Technology engineers have measured the V8's top speed at 170mph.
But it is in mid-range acceleration where this car impresses most. You can be pootling along at 30mph and barely hear the V8 ticking over. But hit the throttle and the wolf immediately shrugs off its lamb's wool coat. The V8 roars into life and, within a second, you're doing 50mph. In another 4.1 seconds you're at the legal limit. Until you hit the accelerator hard, you'd be pushed to know this wasn't a standard S4. The predominant handling characteristic is understeer and, with quattro grip at work, you'd have to be a real hooligan to unsettle the S4 V8.
Cosworth Technology reckons it will take more work to give this machine production standard driveability; we'd say it is nearly there already.
Now we've had a taste of the future, we can't wait for the real thing. The S4 V8 is impressive and will undoubtedly become the ultimate compact cruiser when it tops the new A4 range. It might not give the driving thrills of a BMW M3 - but Audi still has a couple of years to work on that.
At a glance
* Prototype A4 V8 built by UK firm Cosworth Technology
* Uses S8's 4.2 unit in S4 chassis
* 0-60mph in 5.1 secs, 170mph
Article from Auto Express, Thursday 11 Jan 2001
Wow! They stuffed a V8 into an S4
Wonder how much that extra wieght would affect handling characteristics?
[This message has been edited by Kazsim (edited January 15, 2001).]