If an engine note defines a brand then Jaguar would be a growling twin-cam straight six, Porsche a yowling air-cooled flat six, and Audi a guttural five-pot turbo. Audi wasn't the first to lay claim to the straight five-cylinder configuration (Mercedes-Benz, Lancia and Honda have antecedents), but it did define that belting second-order harmony way back in 1977, with the Audi 100E, its first five-cylinder unit.
SEP 21st 2016
Review: Audi TT RS
You are probably now thinking of the chirking, roaring Quattro monsters that battled their way into world rallying history in the Eighties. But while quattro four-wheel drive hasn't left Audi's price lists since, five-cylinder engines have had just intermittent presence, victims of fashion, emissions legislation and costs.
Even Audi's hugely successful small coupé, the TT, didn't have a five cylinder at launch. Instead a lumpen 3.1-litre V6 was crammed under the bonnet in place of the standard four cylinder, which made for a heavy, understeering, thirsty and rather unhappy top model. Mark II TT saw wiser counsel prevail, with the adoption of a 335bhp 2.5-litre five-cylinder in 2009. This was the debut of the RS model, which received a power upgrade to 355bhp in 2013. It was still a heavy engine, however, with a cast-iron block and aluminium cylinder head.
At the launch of this Mark III model, it was clear that not only would there be a replacement RS model, but also that it would have a five-pot turbo. Few, however, expected such radical changes to the engine. The adoption of aluminium for the block has saved 18kg, but a cored-out crankshaft, motorsport-style lightened aluminium timing belt pulleys, magnesium-alloy sump and even aluminium fasteners took the total weight saving to 26kg.
"Since this is all in front of the front axle, this is the best place to save weight," says Stephan Reil, powertrain program manager.
The engine also has variable timing for its twin overhead camshafts and switchable exhaust camshaft lobes to increase exhaust flow at low revs and so speed the big Borg Warner turbo. It produces 394bhp and 354 lb ft from just 2.5 litres and drives through Audi/VW's latest wet-clutch, seven-speed, twin-clutch transmission, which drives all four wheels via Audi's multi-plate-clutch-controlled rear axle.
All this makes for a seriously fast car, its 174mph top speed and 3.7-second 0-62mph acceleration time rivalling anything in the sector – even the mighty Audi R8 supercar only manages the 0-62mph dash in 3.5! Combined fuel consumption is 24.4mpg with the standard 19-inch wheels and tyres, and CO2 emissions are Band J 187g/km.
And it sounds fantastic; that warbling exhaust note redolent of bright headlamps igniting frozen Swedish forests, as a big white rally car yumps its way along snowy tracks with heroes called Stig, Walter, Hannu or Michèle at the wheel.
You need to be a bit of hero yourself, since the turbo power delivery is uneven, sometimes surging forward in the mid range, where at higher revs there might be lots of lovely noise, but a lot less extra thrust. Pressing on, you get used to the lurch of the stability control applying the brakes on the outside wheels, not always when you expected it. Have no doubt, it's quick, but the thrill is mostly in the middle of the rev counter.
The cabin feels quite crowded with its sports seats and razzy steering wheel covered in switches and dials including the engine start picked out in red. It's all immaculately put together and pleasing to the touch and the eye, even if it does take a bit of learning. The seats are comfortable over long distances, which is more than can be said of some rivals and while there isn't much storage space in the cabin, the hatchback hides a 305-litre space, which goes to 712 litres if you fold the vestigial rear seats. The soft-top Roadster has a lot less room as the hood folds into the body.
And like the rest of the TT range, the driver gets Audi's Virtual Dashboard, which is capable of head-spinning permutations with instruments displayed onto the sat nav on Google maps or visa versa. It also displays wireless communications, plays CDs and downloaded streamed music, as well as giving access to virtually all on-line services.
So it's got power and looks, is comfortable and very high tech, but none of those things were major criticisms of the outgoing RS model. The major issue has been stodgy handling compared with its immediate competitors: Porsche's Cayenne and BMW's M2.
Losing 57lb from the very front of the car has helped a lot and the TT's nose turns in with more precision than before. The body is impressively roll-free, but the car feels slightly wayward at high side loadings and the Pirelli tyres get quite a work out when you press on. And while the steering is direct and well weighted, it feels numb and the handling's response to the throttle is woolly compared with its rivals. You can go fast in the Audi, but there are times, as it imperiously sweeps through bends, that you wonder how near the limit is has got to, and in that respect, the car doesn't help you much.
Audi will point to the TT's 4x4 all weather capability and that's true. Rear-wheel-drive rivals won't throw you off the road if it rains, but you'll need to moderate your right foot more. That said, you are paying dearly for the privilege. The TT coupé costs £51,800 and the Roadster £53,550, where Porsche's 718 starts at £39,878 the BMW M2, £44,080.
A huge improvement over its predecessor, the new TT RS has closed some of the gap on its rivals, but be sure, that gap is still there.

Exclusive GRRC Videos
Join the GRRC Fellowship to access year-round exclusive videos, live streaming from events and more. Join now