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.