The key to the RS is its turbocharged 2.5-litre, 20-valve in-line five, an engine configuration deliberately intended to evoke memories, mostly aural, of one of Audi's greatest triumphs on road and track in the original Quattro.
This new engine is substantially more potent, of course, putting out 335bhp and a thumping 332lb ft of torque instead of the 197bhp and 210lb ft of the earlier engine. It is a good-looking motor, too, its cam covers finished in crackle red paint and exposed for all to see rather than being buried beneath a plastic cover.
The key here is to know that the blown five begins kicking out its hefty 332lb ft of peak torque from as low as 1600rpm and maintains this effort all the way to 5300rpm. A close-stacked spread of six gears, all-wheel-drive traction and a smooth-revving engine all combine to produce locomotive-like thrust in virtually every gear well into three-figure speeds.
For an idea of how swift this car can be, consider that it can cover the 30-70mph sprint through the gears in just 4.4sec, and make the same leap using fourth gear alone in 6.4sec. And the all-out sprint to 60mph requires just 4.7sec, a number that convincingly eclipses the Porsche Cayman S’s 5.1sec, for instance. Unusually, there is no performance penalty for specifying a drop-top model over the coupé.
Like previous RS models such as the RS6, Audi has launched a 'Plus' variant of the TT RS as a production swansong. Power is boosted by 20 points to 355bhp and 343lb ft of torque is claimed. The resulting 0-62mph time of 4.4 seconds is enough to make rivals like the BMW Z4 sDrive 35iS look rather sluggish in a straight line.
Anyone who has driven, or heard, an old Audi five-pot turbo working hard will look forward to hearing a reprise in this new RS. And on one level they won’t be disappointed; the distinctive timbre of that resonant hum is successfully recreated. But the throbbing beat of the Quattro has largely gone, replaced by a more penetrating exhaust note.