Iain Dooley, PA senior motoring writer, drive Audi's leaner, meaner and greener refreshed Audi A5 Coupe.

As the self-styled king of niche markets, recent years have seen Audi's model range and sales figures soar. It's no coincidence – the German car-maker has discovered a winning formula in the way it can identify potential in new model sectors. And far from reaching saturation point, growth remains a regular discussion topic with the company executives.

A case in point is its A5 line-up. Initially sold as a two-door coupe, the range has expanded to include a convertible, high-performance models and a four-door fastback. Audi already has a compact saloon with the A4, but it's a testament to its ability to target models at specific customer profiles that the two cars happily co-exist in the Audi range.

And with sales having broken through the million barrier in 2010, the company is clearly doing something right. It keeps doing it too, with regular model updates. This time it's the turn of the A5 range, with a refresh programme spanning cosmetic, interior and mechanical improvements.

In the case of the A5 Coupe, the main focus has been the engine range. Lower fuel consumption and emissions ratings do much to keep the car competitive in a world where economy and CO2 are often the driving factors come purchase time.

A redesigned entry-level 1.8 TFSI petrol motor now boasts 170hp (up by 10), the potential to achieve 49.6mpg and emit only 134g/km CO2. As such, in a perfect example of downsizing, it effectively replaces the A5''s 180hp 2.0-litre petrol motor.

There have also been changes in the diesel line-up, with Audi's familiar 2.7-litre unit now replaced by a 204hp 3.0-litre motor promising 57.6mpg and just 129g/km CO2. Completing the changes is a reworked 177hp 2.0-litre diesel with headline-grabbing 122g/km CO2 and 60.1mpg figures.

Even the flagship S5 hasn't escaped, with its V8 petrol motor now swapped for a more frugal but no less capable forced-induction 3.0-litre V6. Fuel economy jumps to 34.9mpg while it's also a fraction quicker to 62mph too.

Audi's new-found green zeal isn't at the expense of driver enjoyment, though. Keen drivers can still enjoy Audi's switchable suspension, throttle and steering modes. Incidentally, the car's steering is now electromechanical and not hydraulic – a further step to reducing fuel consumption.

Out on the road and the A5 Coupe displays a level of refinement and competence that's hard to match elsewhere in the market. In newly-uprated 2.0 TDI guise, the car proves quick enough on the straight bits to make overtaking safe and packs enough low down torque to make light work of the urban crawl. It's easy to see this car as a frugal urban tool during the week and a brisk grand tourer at the weekends.

Even if you don't touch the car's 'drive select' system, its steering and engine behaviour is entirely predictable. There are more driver-focused cars out there but the A5 delivers a rounded and more mature experience with little hint of any compromise.

Move up to a car with Audi's quattro all-wheel drive system and the subtle improvement in stability and the ease at which the car can change direction is noticeable. Based on the technology underpinning the flagship RS5, it's now more responsive to changes in road conditions, while an optional rear sport differential can be fine-tuned by those drivers seeking an even more thrilling experience.

Although always a stylish car inside and out, Audi's refresh has included a few visual enhancements. Subtle tweaks to bumpers, bonnet and light clusters should help differentiate new from old, while the cabin sees changes to the design of the steering wheel, gear lever, column stalks and minor controls plus new trim and upholstery.

Whether you're after a modestly powerful A5 Coupe or a fuel-sipping, tax-friendly company car, as is always the case with Audi there's no shortage of choice. And, now more than ever, buying something like an A5 is as guilt-free as it gets. With its new range of low-consumption and emitting engines both your heart and your head can rest easy knowing that you made the right choice for all the right reasons.