For the first time in its history, the Audi S5 now has a V6 diesel at its heart. The 3.0 TDI engine, which will be introduced in both the S5 Coupé and the S5 Sportback in late 2019, now produces 342 bhp and delivers up to 516.3 lb-ft of torque to the crankshaft, available between 2,500 and 3,100 rpm.

The 3.0 TDI in the S5 models is the most powerful version in the Audi V6 diesel engine line-up. Both the electric powered compressor (EPC) and mild hybrid (MHEV) systems are embedded in the standard 48-volt main electrical circuit. For the first time in the S5 TDI, a 48–volt belt alternator starter is the heart of the mild hybrid system with maximum recuperation power of up to 8 kW. A DC/DC converter steps this voltage down for components in the 12–volt electrical system. A compact, air-cooled lithium-ion battery with a capacity of 0.5 kWh installed under the luggage compartment floor serves as the energy centre.

Acceleration to 62mph in the S5 Coupé takes 4.8 seconds and and 4.9 seconds in the S5 Sportback, with both reaching their peak at an electronically limited 155mph.