The Volkswagen Group is on a high at the moment, and nowhere is this more true of its engine development. Audi's position within the group means it is usually the first recipient of the latest powertrains. The A4 is the latest benefactor of its common-rail diesel technology.
The 2.0 TDI is the biggest-selling A4, and its buyers should be broadly pleased with their purchases. In mid-range 141bhp form, this is a very smooth diesel, with an impressively revvy accelerator response, a wide power band that runs to 5400rpm (although the engine’s maximum effort lies between 1750 and 2500rpm), little extra noise from cold and general refinement sufficient to mask almost entirely its oil-burning diet.
It pulls vigorously enough in the mid range to feel sportingly brisk, and a well cushioned clutch, a light gearshift and six gears all ease exploitation of its capabilities.
A gear indicator in the dash display suggests early upshifts for lower fuel consumption, but performance in sixth is, as you’d expect, slothful. Use the ’box more fully and this Audi serves up more assertive performance, with 60mph coming up in 9.2sec from a standstill.
Outside of this fleet favourite, the diesel line up becomes a little bewildering. The low-power TDIe version produces 134bhp and 236lb ft, and the only penalty for improved efficiency is 62mph arriving 0.1sec later. The other TDIe produces 160bhp and 280lb ft, cutting the 0-62mph time to 8.4secs. A non-TDIe version tops the 2.0-litre range, developing 175bhp and 280lb ft, slicing another 0.2sec from the dash to 62mph.
In all of its guises, you’ll only suspect this engine is an oil-burner when driving enthusiastically, and even then the distant thrum entering the cabin is actually quite pleasant. For genuinely punchy pace, however, you'd be better off with one of the more powerful versions.
The oil-burner of choice in this regard is the 3.0-litre TDI. With a two-wheel drive configuration, it develops 201bhp and 295lb ft, which makes it good for a 7.1sec 0-62mph. In Quattro models, performance is markedly more swift - 6.1 or 5.9sec for the six-speed manual and S Tronic auto respectively. That's thanks to 242bhp and a thumping 367lb ft arriving between 1400 and 3250rpm.
Petrol buyers have a more straightforward time of it. A 118bhp 1.8-litre TFSI is best left in favour of the 168bhp unit. That engine dispatches 62mph in around 8.0secs, compared to 10.5 for the low power model. Step up to the 2.0-litre TFSI and you'll receive the engine from the Golf GTI, which drops the 0-62 time into the high six second region.