We’ve always been fans of the A4 Avant – its chunky looks, great build and image have ensured that it has remained a top-seller in the Audi range.

Slick marketing has also promoted the desirable, top-spec S line package for just £750 over the price of the SE, which offers goodies such as 18-inch alloys, lowered suspension, body styling and sports seats, and there’s the added incentive of a free Bose sound system upgrade on both SE and S line models.

Now the A4 is available with a 170bhp version of the 2.0 TDI engine for a premium of £935 over the 140bhp model, giving impressive extra punch with identical CO2 emissions and combined mpg – 154g/km and 48.7mpg respectively. It seems like money well spent.

At £24,810 for the Avant SE and £25,560 for the S line, there’s negligible difference in benefit-in-kind tax – I would definitely opt for the S line, given the modest cost, rather than the SE specification of our test car. Aside from the extra kit, there’s a small predicted RV advantage (£125) to be had, according to CAP.

In practice, the 170’s theory works – the slick six-speed ’box is almost superfluous such is the engine’s torque, up from 236lb-ft in the 140 to 258lb-ft from the same 1,750rpm.

That translates to fine mid-range punch and superb overtaking power, though the narrowness of the power band has you constantly grabbing gears and there’s not a great deal of flexibility either side. It means the engine is apt to ‘bog down’ at lower revs – for example, when entering a roundabout in too high a gear. All of this begs the question of what this engine would be like with Audi’s superb S tronic transmission which, in fully automatic mode, should match road speed with the peak torque delivery band.

Though the 2005 facelift did much update the A4, it is beginning to show its age – hardly surprising as the basics of its design date back to 2001.

Verdict
With this firecracker of a TDI engine, the A4 is an executive express that’s beautifully engineered and built, cost-effective and good to drive, with the performance to match its desirability.

Max power (bhp/rpm): 170/4,200
Max torque (lb-ft/rpm): 258/1,750-2,500
Max speed (mph): 134
0-62mph (secs): 8.8
Fuel consumption (mpg): 48.7
CO2 emissions (g/km): 154
On sale: Now
Price (OTR): £24,810