Adding to the speculation train, the use of a bi-turbo system on the already high-strung 420hp 4.2liter V8 for an additional 30hp is very possible although improbable. If Audi is going to use a V8 engine, displacement needs to be increased.
Following Audi's self imposed schedule of having only one RS model on the market at a time, deliveries of the brand new 573hp twin-turbo V10 RS 6 Avant are getting underway for 2008 as the B7 RS 4 ends its production. With RS cars typically having a two year life cycle, the next RS model is expected to debut in 2010 as MY 2011. The most likely candidate to take over from the RS 6 is the RS 5 Coupe since - by that time - it will be in the second half of it's life cycle, although too early for the all-new B8 A4.
With regards to the horsepower wars amongst the German auto makers, Audi had positioned previous RS and S models just above and below the competition, the BMW M3 (420hp) and Mercedes CLK 63 AMG (480hp). And much of the chatter lately in the media seem to be supporting that - as the figures put the RS 5 between 450 and 500hp.
Earlier this year Car Magazine reported the RS 5 will receive the 4.2 liter V8 currently in the RS 4 with the addition of two small turbochargers for an additional 30hp to 450hp and 500 ft-lbs of torque across the rev range. More recently, Road&Track magazine reported that the RS 5 will use the Lamborghini Gallardo derived 5.2-liter V10 like the current S6 and S8 models - but with output bumped up to 500hp.
Adding to the speculation train, the use of a bi-turbo system on the already high-strung 420hp 4.2-liter V8 for an additional 30hp is very possible although improbable. If Audi is going to use a V8 engine, displacement needs to be increased since the RS 5 needs to produce over 480hp to be positioned above the horsepower leading CLK 63 AMG's 480hp. Alternatively, a slightly detuned Gallardo V10 making 500hp seems the most logical candidate. We already know the MLP platform that the A5 uses also serves as the basis of the future A6 and A7 models which are destined to fit the 5.2-liter V10, so engine fit in the RS 5 shouldn't be an issue. The only questionable issue with the V10 is weight distribution adversely affecting handling.
Audi has already marked the importance of the A5 by stating the lineup will be diversified starting with a convertible version, and undoubtedly the RS 5 will also fill a long time void in Audi's model line. Hopefully, we will see a RS 5 concept in 2009.
What engine do you think the RS 5 will get?