MERCEDES-BENZ Cars has revamped its popular C-class four-door sedan and Estate wagon with a subtle nose and tail nip and tuck, new dashboard design and layout, idle-stop ‘Eco’ technology in a revised diesel strategy, and improved safety.

Plus the old five-speed automatic transmission steps aside for the company’s 7G-Tronic seven-speed automatic gearbox across range, for reduced fuel consumption and carbon emissions.

Yet prices for the new W204 Series II vehicles remain the same for the volume-selling four-cylinder CGI direct-injection petrol versions – $58,900 C200 and $67,900 C250 BlueEfficiency – while the long-running C220 CDI turbo-diesel gives way to a pair of four-pot diesel models – the C200 and C250 CDI.

Now it costs $1270 less to go diesel, but – as the name implies – the C200 CDI offers less grunt than before.

Finally new six-cylinder sedan variants in C300 3.5-litre CGI V6 petrol and C350 3.0-litre CDI turbo-diesel guises arrive from September, in time for the long-time coming C-class Coupe version that acts as the belated replacement for the discontinued CLK coupe, as well as the C 63 AMG sedan and Estate.

Minute visual familiarity with the old car is helpful in picking the 2000-plus changes wrought upon the newcomer from any distance.

These include new headlights, grille, bumpers, air intakes and bonnet, with the latter now made from aluminium like the front guards, bringing a 10kg weight saving. Look for a more pronounced ‘V’ shape.

The newly optional bi-xenon high-intensity discharge headlights boast a stylised ‘C’ motif, which connects it with the fresh tail-light lenses, apparently. They also include more LEDs. The rear bumper is now designed to emphasise width.

Less eyestrain is necessary to pick the changes inside, with a E-class-style horizontal-themed dashboard replacing the previous version. A trio of sunken dials featuring a TFT display, a new steering wheel, and an integrated rather than pop-up centralised screen for audio and available satellite navigation data are further highlights.

It should also feel better thanks to higher quality materials, grains, trim, and surfaces, while Mercedes says there is now more obvious differentiation between the Elegance (luxury) and Avantgarde (sporty) models.

On the drivetrain front, the 7G-Tronic seven-speed gearbox is now standard across the range, and helps bring considerable efficiency improvements to all engine choices.

The all-new 1796cc 1.8-litre turbocharged direct-injection twin-cam 16-valve BlueEfficiency four-cylinder petrol unit – dubbed CGI but the badge no longer exists – that debuted in Australian C-classes 14 months ago in C200 (135kW at 5250rpm/270Nm at 1800rpm) and C250 (150kW at 5500rpm/310Nm at 2000rpm) formats still deliver the same power and torque as before. However, they now use less fuel. The former sprints to 100km/h in 8.2 seconds (same as before) while the latter is 0.2 seconds faster at 7.2s.

Astonishingly, despite their disparate outputs, both return 7.2 litres per 100km (previously 7.3 and 7.7L/100km respectively) and emit 167 grams per kilometre of carbon dioxide emissions (before: 171 and 180g/km respectively).

Most C-class buyers choose four-cylinders, but the 170kW/300Nm 2996cc 3.0-litre V6 C300 petrol model that arrived in late 2009 has since grown to a 3498cc 3.5L V6 channelling 185kW at 6500 and 340Nm from 3500-4500rpm while consuming just 8.3L/100km and 194g/km of CO2.

The bigger news is Mercedes’ new diesel strategy.

Out goes the C220 CDI (2148cc 2.1-litre turbo-diesel generating 125kW/400Nm, 6.3L/100km, 173g/km, 8.4s 0-100km/h), and in come the C200 CDI (2143cc 2.1L, 100kW at 2800rpm/330Nm at 1600rpm, 5.4L/100km, 143g/km, 9.2s) and C250 CDI (2143cc 2.1L, 150kW at 4200rpm/500Nm at 1600rpm, 5.1L/100km, 134g/km, 7.1s). This time the more powerful unit returns even more impressive frugality.

Both Euro-5 emissions compliant CDIs employ Mercedes’ new Start/Stop engine technology that extinguishes the engine at idle to conserve fuel/cut pollution.

When it lobs in later in the year the C350 CDI will be a non-AMG performance flagship, realising 195kW at 3800rpm, 620Nm from 1600-2400rpm, 6.1L/100km, 160g/km and 6.0s for the 0-100km/h time from a 2987cc 3.0-litre V6 turbo-diesel. In contrast the existing 165kW/510Nm C300 CDI can ‘only’ manage 7.4L/100km, 196g/km and 6.9s.

Mercedes has also ushered in nine new driver assistance systems using high-tech sensors from the larger E-class. Most are not available on rival products.

Briefly, Brake Assist Plus recognises an impending rear-end collision using radar sensors, to help apply maximum necessary brake force.

Adaptive High Beam Assist alters the light intensity according to oncoming traffic, while using the stability control system Active Lane Keeping gently brakes a car to keep it on the straight and narrow.

Active Blind Spot Assist applies braking so the car won’t hit an objects that might be outside of the driver’s field of vision, and Attention Assist alerts a drowsy driver with a chime and ‘cuppa’ icon.

Distronic Plus is radar-controlled cruise control that slows down, stops and then reaccelerates your car according to the velocity of the vehicle ahead Parktronic helps guide a car into a tight parking spot (but does not actually turn the steering wheel VW-style).

Pre-Safe prepares all safety systems for an impending impact for maximum protection while Lane Keeping and Blind Spot Assist warn the driver that he/she may be slowly off course or is about to hit something lurking outside of the person’s vision respectively.

Finally, the 2012 C-class introduces new telematics functionality within a large display format that promises greater operating convenience thanks to the migration of the plug interfaces from the glovebox to the centre console armrest.

Mercedes’ upgraded COMAND multimedia system that debuted in the 2009 E-class is also now available in the C car (standard from C250 upwards), providing in-car internet access for the first time (when stationary). With the optional GPS system it offers SUNA traffic info, Google Map data, and route importation capability via an SD card, among a host of other innovations.

The W204 Series II is a rear-drive only proposition for Australians due to there being no right-hand drive engineering for Mercedes’ four-wheel-drive system known as 4Matic.

As before, all models employ adaptive damper control, as part of the three-link MacPherson strut front and multi-link rear axle design that is a thorough redevelopment of the original W201 190E pioneered in production cars in 1982.

Dubbed ‘Agility Control Suspension,’ it automatically softens or firms up the damper pressure according to how the vehicle is being driven – softer when the car is being driven sedately and firmer for when pressing on.

The steering is of the speed-sensitive rack-and-pinion variety, while other technologies on offer include hill-start function called ‘Start-Off Assist’ and a gentle wiping of the brake discs if damp conditions prevail to increase their effectiveness.

Mercedes says that the W204 successfully passed more than 100 crash tests, some which exceed current legal requirements.

All models include ESC, eight airbags (dual front, front side, rear side and curtain) and Mercedes’ Pre-Safe anticipatory occupant protection system and Agility Control Suspension.

Even the base C200 features anti-whiplash head restraints, 17-inch alloy wheels, Artico leather-like upholstery, dual-zone climate-control air-conditioning, rain-sensing wipers, a leather-trimmed steering wheel and transmission knob, a multi-function steering wheel with cruise control and Bluetooth connectivity and streaming.

Finally, the C-class offers a range of new options, including a restyled Sports Package, a Comfort Package, heated and cooled Climatised Seats, an upgraded Thermotronic climate control system, and fresh wheel designs.

All these changes and improvements should help Mercedes-Benz maintain its domination in the upper medium ($60,000 and over) sector, which sees the outgoing sedan and wagon’s 1732 sales to the end of April being some 450 and 536 units ahead of the BMW 3 Series and Audi A4 respectively – although the latter’s figure shrinks to just 158 sales if the closely related A5 Sportback’s numbers are also included.

However, despite this margin, C-class sales are down 12.6 per cent so far this year, in a segment that is running 15.9 per cent behind last year’s tally.

Mercedes will not release volume projections, but the company expects the Series II to help the range push well past the 6000 unit barrier in 2011, with about 10 per cent of these (600) made up of the Estate. Diesel sales currently account for 40 per cent, but this may rise with the advent of the new entry level C200 CDI.

Since the W204 went on sale in Germany in early 2007 more than one million have been produced, and is part of an 8.5 million-selling series of compact Mercedes cars that stretch back to the W201 ‘190E’ launched 29 years ago.