CITROEN and diesel go together like bread and butter, but in recent years what was almost a USP has become diluted with technological advances from other manufacturers. In fact, Citroen's indirect injection engines had become almost old-hat in the face of advanced new units from other mainstream manufacturers, many of which eclipsed Citroen on economy and emissions.

But now PSA Group, Citroen's parent, has bounced back with state of the art common rail diesel engines that make some startling claims on fuel consumption and exhaust cleanliness. Economy is improved by a claimed 30% over previous engines, while carbon dioxide emissions have been reduced by 20%.Initially, the new 2.0-litre HDI (high efficiency direct injection) engine can be had only in the Xantia and with just one output ù 110bhp ù but its availability has been increased to include the LX grade.

In this guise, it replaces the old indirect injection 2.1 TD, but lower output versions retaining the same capacity will filter through the range to replace the existing 1.9-litre turbodiesels in other Xantia variants by next summer. At the same time the lower medium Xsara will also gain a common rail diesel, unifying most of the Citroen car range with state of the art technology. The new engines accompany a series of range-wide equipment enhancements that confirm the Xantia as one of the best-value cars in the sector. ABS brakes and Trafficmaster Oracle, featuring real-time traffic information with TM's new nationwide network of 7,000 sensors (the 'blue poles' we have all seen cropping up on major routes throughout Britain), now become standard from LX upwards, while SX models gain a six-disc CD autochanger.

These improvements haven't come a moment too soon as the Xantia is now in the twilight of its life and badly needs a rejuvenating shot in the arm. As tested here, the Xantia HDI SX costs ú18,460 on-the-road, ú435 less than a Volkswagen Passat TDI 110 SE, which now comes with air conditioning as standard.