Did you know quattro GmbH experimented with a 3.0 TFSI twin turbo engine for the B7 RS 4 alongside the high-revving 4.2 V8? It’s true, and though the high-rev 4.2 FSI was chosen as the better choice it is also the main reason that there likely will not be an RS 5 plus.
Talk of a planned 600 bhp RS 6 plus also led CAR Magazine to ask quattro GmbH product boss Stephan Reil about the likelihood of an RS 5 plus model. According to CAR, Reil stated, “The naturally aspirated 4.2-liter V8 already has over 100 bhp per liter – it could perhaps produce 455 bhp to 460 bhp, but that’s a 2% difference and you would not feel it.”
Turbocharged engines like the 2.5 TFSI TT RS plus and the 4.0 TFSI in the upcoming RS 6 naturally lend themselves to a more preferred 8-10% gain. While the high-rev 4.2 FSI is already tuned to nearly its performance maximum, there’s still room in its turbocharged counterparts. Had Audi chosen to go with that 3.0 biturbo it had examined during the gestation of the B7 RS 4, things might have been different. As for now, there’s no significant power bump Audi could offer for the RS 5 as it is produced today.
So does that mean there won’t be an RS 5 plus? More than likely the answer is no, but that doesn’t mean it’s entirely out. With the C7 RS 6 Avant quattro GmbH did make a ‘plus’ model that offered the same power with some lightening elements like greater use of carbon fiber. The R8 V10 plus also goes the route of lightened weight rather than raised power. If there were to be an RS 5 plus, it would have to follow this model. Reil and his team could elect to go the route of carbon fiber body panels or the like to pull some weight out of the car, though given the costs of crash testing, etc. this may be easier said than done.