Art of feinting by numbers

Mercedes is launching the E-class under its 'BlueEfficiency'. Photo / Supplied

The new E-Class coupe and sedan point to a "greener" new direction for Mercedes-Benz, where what you see on the badge at the rear is not necessarily what you get up front under the bonnet.

The luxury German carmaker has pretty much always made model designations clear: the 350SE sign on the boot lid pointed to a 3.5-lite V6 engine up ahead. Likewise the 280ML badge and a 2.8-litre unit. There have been minor aberrations: A C240 model had a 2.6-litre engine. The C200 ran with a 1.8-litre.

But the new world order for cleaner-burning and more fuel-efficient engines, particularly in more mainstream models, is clear - every carmaker agrees: "The future is small capacity with turbocharging."

Mercedes-Benz has delivered such engines in the E-Class coupe and sedan under its "BlueEfficiency" banner.

Apart from smaller displacement and turbocharging, they include improved aerodynamics (a world-leading drag co-efficient of 0.25 for the sedan and 0.24 for the coupe), a more efficient alternator, direct fuel injection, on-demand power steering pump and fuel pump, lower rolling resistance tyres, and an optimised air-conditioning compressor.

"We have a deep commitment to the environment and a history of environmental friendliness," says Roger Zagorski, general manager of the Mercedes-Benz car group in New Zealand.

"With BlueEfficiency we can remind ourselves and the public of that history. Longevity in the automotive industry is pinned to environmental issues."

The new engines fall under the "less is more" philosophy, using four-cylinder turbocharged engines with lower displacement in place of bigger, non-turbocharged engines. Key benefits include lighter weight, reduced internal friction, improved economy and cleaner CO2 emissions.

The carmaker can be expected to push the claims of its smaller, twin-turbocharged diesel unit, a 2.1-litre four-pot badged E250 CDI. So too its entry-level petrol unit, a 1.8-litre single-staged, turbocharged, direct-injection four-cylinder wearing the E250 CGI moniker. They are the first four-cylinder engines ever to appear in the E-Class range in New Zealand.

The top E-Class diesel also carries the new nomenclature - it's a 3-litre V6 with a E350 CDI designation. Same with the top-range E500 and its 5.5-litre V8. The only model with an accurate badge is the E350 - it carries a 3.5-litre V6 petrol unit.

"The new nomenclature won't be determined by engine capacity or power," says Zagorski.

It's a numbers game. How the carmaker arrives at the E250 CDI badge, for example, remains known only to its boffins. The 2.1-litre turbodiesel delivers 150kW at 4200rpm and a whopping 500Nm of torque at between 1600-1800rpm. Perhaps halving the torque is the clue to the badge. Or does it have something to do with the claimed fuel economy of 5.3 litres/100km, or CO2 exhaust emissions rating of 139g/km?

The boosted 1.8-litre E250 CGI petrol unit puts out 150kW at 5500rpm and 310Nm between 2000-4300rpm. Where's the clue there? Its claimed economy of 7.3 litres/100km and CO2 rating of 174g/km offers little too.

The 3-litre V6 turbodiesel in the E350 CDI produces 170kW at 3800rpm and 540Nm between 1600-2400rpm. No obvious clues there either. Not unless the 6.9 litres/182g/km hides something.

The E350 and its naturally aspirated 3.5-litre petrol V6 comes closest. It delivers 200kW at 6400rpm and 350Nm between 3000-5100rpm. At least the engine capacity and torque output point to its badge. Obviously nothing to do with the 9.4litres/210g/km split.

The 5.5-litre V8 in the E500 is another blind alley. Its 285kW at 6000rpm and 530Nm between 2800-4800rpm offers little in the way of an answer. Neither does the 11 litres/258g/km the carmaker claims for its premium model.

The model names might confuse but Mercedes-Benz leaves nothing to chance about the cars themselves. Take it as read that the coupe and sedan come with the latest in everything.

Safety innovations include nine airbags, Attention Assist driver fatigue detention, the Intelligent Light System, Adaptive High-beam Assist, Distronic Plus radar-guided cruise control and the Pre-Safe Brake device.

The driver fatigue system uses sensors to help keep the car on the straight and narrow. The outline of a steaming cup of coffee appears on the instrument panel - a hint to the driver that it's time for a break.

The new E-Class is the first Mercedes-Benz model to feature a combination of AIRMATIC air suspension and an electronically controlled damping system that adapts the damper characteristics with continuously variable control individually for each wheel. It is standard on the E500 and optional on some of the others.

The sedan is bigger inside and out than the outgoing model and contains styling cues from an E-Class range that dates back to 1947.

The quad headlight look was pioneered on the 1995-2002 model E-Class and the rear wheel arches hark back to the "Ponton" models of the 1950s. The instrument binnacle borrows from the best years, too.

Mercedes-Benz began developing the new E-Class seven years ago.

Since then it has built 1400 prototypes, conducted 150 crash tests and 17,000 virtual crash tests. It says the model is "arguably the safest car in its class".

The E-Class coupe replaces the CLK two-door. It is actually built on the smaller C-Class platform, although pretty much everything else comes from the E-Class shop.

The coupe's body is longer and wider than the CLK but adopts its twin-headlight arrangement with E-Class sedan styling. It also borrows from the past - the design was inspired by the 1955 "Ponton" S220 coupe.

The new sedan and coupe are priced between $104,900 and $172,900.