Audi A6: Diesel decisions

TDI PD v Common Rail

At first glance, the diesel range in the A6 seems straightforward. There are three TDI engines - a 2.0-litre, 2.7-litre and a 3.0-litre - the most powerful coming with quattro four-wheel drive as standard.

Simple enough you'd think. But Audi, along with Volkswagen, recently introduced a new 2.0 TDI engine - a common rail unit which is much more refined and quieter than the old TDI PD (Pumpe Duse) engine and returns better economy.

The introduction of this new engine coincided with the launch of the facelifted A6 in October 2008, so all revised cars benefit from this smoother TDI.

Punchy but noisy!

The engine is still badged as a TDI, so if you're looking at nearly-new models in the Audi, Volkswagen, Skoda or SEAT range fitted with a 2.0 TDI, it's worth checking which engine it is.

The newer unit is certainly quieter, but still fairly vocal on start-up. However on the move it is far smoother and more refined, with less clatter at high revs. Of course that's not to say the old engine is terrible. Far from it.

True, it feels a little lumpy and noisy compared to newer diesels, but it has plenty of punch from low down and strong in-gear pace. So, while it may be the entry-level diesel it isn't sluggish and 0-62mph takes a respectable 10 seconds.

Current mileage: 25939

Average mpg: 35.8