WITH an ever-expanding range and phenomenal sales increases, Audi is conscious that it is treading a tightrope between premium brand and volume seller.

However, it is determined that however many cars it sells, it will stay firmly planted in the premium sector.

The Audi Group once again set records for deliveries, revenue and key earnings data in 2011.

The brand sold more than 1.3 million cars, at the same time increasing revenue to 44.1 billion euros, and the operating profit rose to more than 5.3 billion euros.

Chairman Rupert Stadler says: “Never before have we had such a large increase in deliveries in a single year. It was the most successful year in the history of our company. We want to continue on this path in 2012 and grow more strongly than the market as a whole.”

It was a good year, too, for BMW and Mercedes-Benz, but while the big three German premium brands have been putting on sales, the credit crunch and subsequent years of economic turmoil have had a damaging effect on some of the volume sellers in the D sector.

There can be no denying that the volume sellers and the premium brands are coming closer together, at least in terms of the numbers of their cars on the road.

It could also be said that Audi is a company driven by the desire to be the best at building luxury cars for the masses – and the car that is responsible for the biggest chunk of those sales is the A4.

It has defined what Audi believes a great luxury car should be, and that’s a set of rules it is sticking to. That’s partly why the A4 has barely seemed to change down the years, while actually changing an awful lot to deliver a more composed drive with cleaner, more fuel-efficient engines.

The latest version, which went on sale this month, has a sharpened front end, some changes to the lights both front and rear, a slightly different grille and one or two other tweaks. You might say it is a tad prettier, you certainly would not say there is any radical change.

The more significant changes are under the skin, with a series of impressive redeveloped and new engines. Company car drivers and their fleet managers are under more pressure than ever to reduce costs, so Audi has delivered a solution with CO2 output figures as low as 112g/km, and 65mpg potential fuel economy.

You can imagine the fleet managers and company car drivers sitting up in their chairs as they study these figures.

Six TDI turbo diesel options join two turbocharged petrols, with two of the diesels earning Audi’s special TDIe designation reserved for its most frugal cars. They are 134bhp and 175bhp units respectively, but there’s actually relatively little to choose between them on the road or even on paper, where the more powerful engine is almost as efficient as the entry-level one.

The most remarkable thing about these new diesels is how smooth they are, especially at low revs. Reducing cruising revs helps to boost fuel economy, and the new breed of common rail motors are happy to be driven down to just 1,000rpm, while still picking up smoothly.

The 134bhp TDIe is likely to be the best seller – and the performance figures are by no means the only reason why this will be the A4 of choice for many drivers.

Even at motorway speeds it provides a hushed experience, but it has a gutsy side to its character, too, giving it a liveliness not matched by its more powerful partner.

The A4 is a very fine car to drive. It has a long wheelbase which helps to make it feel stable at a cruise, and there is plenty of grip available from wide tyres.

It’s not what you’d call inspiring or breathtaking, but it’s not meant to be. It’s designed to be a fussfree luxury compact executive car that people will be happy to see on their drive.

Watch out for another new model in the line-up, not available to test at launch. Audi has also introduced a 1.8-litre petrol version that promises the economy of a diesel with added refinement.

The RS4 Avant – one of Audi’s finest achievements – is also due to come back into production later this year. Can’t wait.

fact file

Audi A4 2.0 TDIE 136 SE

PRICE: from £25,910

ENGINE: 2.0-litre turbodiesel producing 134bhp and 236lb.ft

TRANSMISSION: six-speed manual gearbox driving the front wheels

PERFORMANCE: top speed 133mph, 0-62mph in 9.3 seconds

ECONOMY: 65.7mpg

CO2 RATING: 112g/km