Peugeot has just added weight to the argument for ultra-green big diesel engines to replace powerful petrol units by adding potent oil-burning newcomers to the 407 saloon and estate range.

There's no doubt about it punchy diesels and their environmentally-friendly credentials are eating into the sales of gas guzzlers, and the newcomers are no slouches, either.

Peugeot's 407 line-up now features an impressive six-cylinder diesel engine, a 2.7-litre 205 horsepower twin-turbo unit that was first seen in the 407 Coupe model.

Customers have to specify the range-topping Executive trim to get their hands on the 407 2.7HDi, and it reaches Britain this May.

Supplementing the V6 HDi Diesel engine, the Executive model can also be specified with the 3.0-litre V6 petrol automatic powerplant.

A new Sport model also gets the choice of a zippy diesel, the 2.2-litre HDi, which has 136 brake horsepower on tap.

The Sport also comes in 2.2-litre petrol form, too, and Peugeot has also upgraded specifications, and the trim levels now feature as S, SE, Sport and Executive designations.

The S model has generous standard equipment, while SE specification adds items like automatic windscreen wipers and headlamps, tyre pressure sensors, and electrically folding door mirrors. The new Sport version further adds powered adjustment for the leather-trimmed front seats, a six-disc CD autochanger, rear parking sensor, and a colour information screen.

A Bluetooth hands-free phone kit is also fitted as standard, as it is on the SE model.

All Executive models take the fully-integrated Peugeot RT3 system combining single CD/RDS radio, integrated GSM mobile telephone colour satellite navigation, and voice activation.

Executive kit also includes xenon headlamps, rear seat side airbags, full leather interior, laminated side windows, heated front seats, rear side window sunblinds, and a rear screen sunblind on saloons only.

The 407's equally impressive safety builds in electronic stability and seven airbags on all variants, which has been recognised by the awarding of a maximum five-star Euro NCAP rating.

Estate models are also well-fitted, adding a panoramic glass roof to other standard saloon items such as digital air conditioning, remote locking, and Smartnav. Prices of all the revised 407s will be released nearer the launch date.