Volkswagen Group has had to delicately balance its four mainstream brands, ensuring they do not challenge each other for fleet sales.

They still do of course - Seat, Skoda and Volkswagen models in particular appear as competitors on numerous fleet choice lists – but the brand with arguably most to lose as the others boost their quality levels (from trim to specification to performance) is Audi.

The group’s premium marque has itself come from the 1980s wilderness to justifiably claim its place among the German elite of BMW and Mercedes-Benz.

In many ways it sits neatly between the two, offering a taste of BMW’s out-and-out driver thrills with the high-quality interior trim fittings of a Mercedes-Benz.

Does this make it a jack of all trades, master of none? In a sense yes, but does this matter? Actually, no. While Audis don’t offer the performance thrills of BMWs, they will more than satisfy most drivers. Likewise, interior quality and design does not quite match Mercedes’s but it is still a pleasant, comfortable place to be. And in both cases, the gaps are closing.

Most company car drivers want a combination of the two and this is where Audi’s strengths sit. It is also increasingly delivering on CO2 and fuel efficiency, bringing down emissions to such an extent that in some model segments it is actually the market leader, usurping BMW.

So to our latest long-termer, the A6 Avant. Clearly an Audi – the company was one of the first manufacturers to recognise the benefits of offering a familiar family face across its car range – it has strong road presence without having the design flair of, say, a Mazda6.

The Avant is function and form: the boot space is 565 litres with seats up, 1,680 with seats down. Compare that with the BMW 5 Series (560/1,670) and Mercedes-Benz E-class (695/1,950). Not surprisingly it splits the two.

It’s a similar story in running costs. Over four years/80,000 miles, the Avant model on test costs 48.5ppm. A comparable 5 Series is 49.25ppm while the E-class is 47.07ppm. The Audi’s strengths are fuel costs and SMR where it undercuts the other two.

And of the ongoing VW Group challenge of Audi versus Golf versus Skoda versus Seat? For now, the Audi A6 still sits comfortably ahead of the others in terms of quality, technology and driver enjoyment. Its badge remains premium, although its running costs are anything but.

Stephen Briers