AUDI Australia will offer no fewer than 21 variants of its facelifted A5 range, with 20 of them arriving in Australian showrooms in April.

That's not even counting an almost endless list of options and variations that can include almost any colour of the rainbow for those willing to shell out up to $4500 extra and wait a few more weeks for delivery.

The new range, in the same coupe, cabrio and Sportback body styles of the current A5/S5 line-up that was launched with the coupe way back in 2007, now can be had with a choice of six engines, not counting the thumping V8 of the flagship RS5 Coupe that is set for its own refresher later this year.

In a big plus for both the environment and customer wallets, 13 of the new models come with engines that achieve the benchmark 7.0 litres per 100km combined fuel consumption, qualifying them for luxury car tax breaks.

New, thriftier engines and a raft of fuel-saving changes such as electro-mechanical steering and idle-stop on every powertrain result in a range-wide fuel efficiency gain of about 18 per cent.

Audi is relying on the new powertrain line-up and minor changes to the exterior and interior to stem last year’s A5 sales decline. In 2011, sales of the A5 slipped to 1957 vehicles, down about 15 per cent on its 2010 peak.

Many of the changes to the revised A5 come courtesy of Audi’s recently renewed uppercrust models, the A6, A7 and A8.

Helping to shore up A5 sales will be two cheaper variants, the $66,900 1.8 TFSI Coupe and Sportback, which reduce the price of entry to the A5 range by about $2000 in the case of the Sportback and $3500 for the new Coupe.

This 1.8-litre turbocharged and dual-injected four-cylinder newcomer to the A5 engine line-up is the most frugal petrol powertrain in the class, achieving 5.8 litres per 100km and emitting just 134 grams of carbon dioxide per kilometre.

The 1.8 TFSI engine – developing 125kW of power at 3800rpm and 320Nm of torque from 1400rpm - matches the performance of the previous entry-level 2.0-litre petrol engine, but it gives up about 30kW and 30Nm compared with new the 155kW/350Nm 2.0-litre TFSI.

The 1.8 TFSI takes 8.2 seconds to reach 100km/h, compared with 6.4 seconds for the 2.0-litre version.

Also new to the A5 – although not to the Audi range – is the acclaimed 2.0 TDI diesel four-cylinder engine that brings even more frugal motoring to the A5, sipping just 4.7L/100km on the combined cycle test and emitting just 123g/km of CO2.

Audi says this is also a class best, although that might only be until BMW’s 3 Series 2.0-litre diesel - now in its its new sedan range with a claimed 4.5L/100km and 118g/km - debuts in its next-gen '3' coupe and cabriolet.

The Audi four-cylinder diesel joins the 3.0 TDI 3.0-litre V6 diesel, which was the only oil-burning engine of the previous range.

This 180kW/500Nm V6 powerplant has come in for some tweaks to rein in fuel consumption from an already thrifty 6.7L/100km to 5.7L/100km, with CO2 emissions now just 149g/km.

Topping the standard A5 range is the new 200kW 3.0 TFSI petrol V6, making its first appearance in any Audi vehicle.

In bad news for V8 fans, the sporty S5 Coupe gives up its 260kW 4.2-litre FSI V8 for the supercharged 3.0-litre TFSI V6 that bangs out 245kW and 440Nm.

The good news is that this engine, which was already available in the A5 cabrio and Sportback, is 0.7 seconds quicker than the V8 over the 0-100km/h sprint, stopping the clocks at 4.9 seconds.

And better still, the smaller engine uses about 25 per cent less fuel, at 8.1L/100km, which is the primary reason for the downsizing.

The two four-cylinder entry models in the new A5 range, the 1.8 TFSI and 2.0 TDI, come mated with an eight-step CVT ‘multitronic’ automatic transmission that powers only the front wheels, while all other models get Audi’s acclaimed quattro all-wheel drive system and the S-tronic dual-clutch seven-speed auto.

The only engine available with a manual gearbox is the 2.0 TFSI, in the Sportback and coupe, as an alternative to the dual-clutch auto.

Only committed Audi fans will be able to pick the external changes to the A5 models, with a couple of grille trim changes and new LED headlights that have a wavy line of light around the lens for daytime running.

Eighteen-inch alloy wheels are now standard, although 19-inch and 20-inch items can be optioned in the 10 alternative wheel styles on the extras list.

Inside, the switchgear has be simplified and tidied, including the LCD-screen management interface. Bluetooth audio streaming is now standard, along with a new-look steering wheel borrowed – like many fresh items – from the A8 and A6.

Audi driving aids – including the A6-style drive select system that adjusts a range of functions such as the suspension and steering to suit comfort, driving style and more efficient motoring – head a long list of packs and options.