After having found fans of the 3.0-litre TDI V6 when it was slotted into the S7, S6, and S5 TDI models, Audi’s gone and shoved the same big oiler in its A4 compact executive saloon, giving the already-capable machine another range of talents, as well as the ability to duck under the new WLTP & EU consumption & emissions standards.
Under the familiar S4 form lies that big 6-cylinder diesel, putting out 255kW and 700Nm, with power going to all-four wheels via a proprietary Quattro system and an excellent 8-speed automatic. 100km/h is cued up in just 4.8-seconds, while the top speed of the thing is limited electronically to 250km/h to prevent it from taking off and flying to the moon.
It’s worth noting that while Europe won’t get a petrol-powered S4 (or S5, S6, or S7), the replacement engine puts all of the cars it powers to within spitting distance of what their outgoing-generation petrol siblings used to do. So there’s really no loss here in exchange for mountains of torque and better fuel efficiency.
At this point you’ll probably want to do this writer’s head in by pointing out that diesels also suffer from heinous levels of turbolag, and you’d be right. But Audi’s fixed that because not only is this a large diesel motor, it’s also a mild-hybrid. As such the 48V belt-driven starter allows for a little bit of electric shove when the turbos would normally be spooling up, and it also manually drives the turbocharger when the exhaust gasses fail to, all in order to effectively eliminate turbolag.
With the belt-starter, up to 8kW and 60Nm can be recuperated effectively. And thanks to a DC/DC converter, the 12V electrical system that the rest of the car runs also gets to use the juice from the air-cooled .5kWh lithium-ion battery under the boot floor.
It’s suggested that this S4 TDI, which was formulated to keep within EU & WLTP guidelines, will only exist in Europe, whereas the rest of the world will continue to enjoy petrol-firing models for the foreseeable future. The Audi S4 in any guise will put up a formidable fight against competition like the AMG C43 and BMW 340i, and this writer always roots for the underdog.
By the way, Audi Australia has not confirmed the S4 TDI for local offering. But considering that its other S-iblings with this engine have all been ruled out, we’d be very surprised if the line differed for this car.
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