Audi A6 2.0 TDI SE

The range's cheapest model, powered by the same engine as our Octavia, the 2.0 TDI SE costs ΂£24,020 and slots in below the 222bhp 3.0-litre oil-burner - which starts at ΂£31,930.

The common-rail TDI gives 44.8mpg on the combined cycle. Add a 70-litre fuel tank, and the 1,540kg saloon can travel up to 690 miles between fill-ups. And if you add CO2 emissions of a mere 169g/km, economy-minded executives should come flocking.

Next to it, Mercedes' similarly powerful but more expensive E220 CDI looks costly, so what about the Volvo S80 D5? At ΂£23,303 it's tempting, and the 172g/km emissions are low. But the Swede still doesn't meet Euro IV legislation, incurring a three per cent tax penalty. So far so good for the Audi, but unfortunately it can't maintain its momentum. The chief problem is engine noise: the 2.0 TDI is no quieter here than in the VW Golf or Skoda Octavia - and that is a surprise. It's intrusive when accelerating, and although it settles at steady speeds, it's neither as refined nor relaxing as it should be.

Straight-line performance is nothing special either, with 0-60mph taking 10.3 seconds. But the meaty mid-range torque means you're rarely left trailing around town. Teaming this motor with a manual box doesn't show it in its best light, though - the shift is slack and highlights the fact that executive saloons are better with auto boxes. But here that costs an extra ΂£1,400, and hits economy and performance.

In other regards, the Audi is impressive. Cabin quality and design are immaculate, and the A6 is an eye-catching shape. The big 18-inch alloys look smart, although they spoil the ride quality. These are optional, and combined with the other extras fitted, pushed our test car's price to ΂£31,180. And there's nothing basic about that!