Motoring (Road Test): A lot more hum than rumble - The diesel success story continues, thanks to cars as sophisticated as Citroen's Xantia. But power and economy don't always mix

DIESEL sales in the first half of the year were 60 per cent up compared with last year's and higher, at 140,000, than for the whole of 1991. By the year's end, more than one in five new cars will be powered by derv-oil. The boom is not driven only by the promise of fuel economy - typically 20-30 per cent better than for a petrol car of comparable price and performance. The improved choice of models, from about 30 only 10 years ago to about 150 now, means more buyers are trawled into the diesel net.

Citroen's new D and TD Xantias are particularly significant, coming from PSA, the diesel market leaders. Powered by what are widely regarded as the most refined four-cylinder engines available, if not the most frugal, they hit the UK market ahead of Rover 600 and Ford Mondeo competitors in the lucrative fleet sector that Citroen is targeting. In the five-door Xantia, PSA also has one of the most roomy and accomplished cars in the big-selling Mondeo/Cavalier class.

At pounds 10,895, the 71-horsepower 1.9D costs the same as the petrol 1.6i, so there is no premium to pay for the more economical engine. Turbo- diesel prices range from pounds 12,795 for the LX (and the petrol 2.0i LX) to pounds 15,995 for the test VSX, powered by the same high-torque 92-horsepower engine.

Down-range Xantias, petrol and diesel, inherit the self-levelling gas/oil 'springs' of the outgoing Citroen BX, with the added refinement of self- steering rear wheels that point into corners to improve handling and stability. The SVX models have a more complex computer-controlled system that, according to conditions, adjusts the suspension between supple (for ride comfort) and firm (for crisp handling) to give the best of both worlds. While this works brillantly, the cheaper alternative is so effective that anything better hardly seems worth the extra money.

The 1.9TD's engine, when it is idling, can be mistaken for a traditional, rumbly diesel. On the move, however, the clatter gives way to a gruff hum, so muted when cruising that it is barely audible. Citroen claims the Xantia is quieter than BMW's forthcoming 325 turbo-diesel. At the extremes of the engine's restricted rev range, the TD feels flat. Between 2000 and 4500rpm, though, torque increases to give snappier mid- range acceleration than most petrol rivals. Although you are encouraged to change down by a light and precise gear-lever, there is little need to do so: even in long-legged fifth - geared for relaxed cruising rather than pep - there is power in reserve for overtaking. Use all the TD's performance and economy suffers. Exploit the turbo- thrust sparingly and more than 40mpg is attainable.

With or without Hydractive 2 suspension, the exceptionally smooth and fluent ride of the Xantia is marred only by occasional 'thunks' over sharp bumps and deep potholes. Such refinement has not been achieved at the expense of sharp handling. The steering (power assisted on all Xantias) is very responsive and the TD's poise and security exemplary under hard cornering. If not an exciting car, Citroen's newcomer is a pleasant and rewarding one for the enthusiastic driver to hustle. Because the controls are so sensitive, however, coarse handling is punished by jerkiness, especially on the brakes. Clumsy drivers should look elsewhere.

The Xantia's long-distance comfort owes more to its quiet engine and supple suspension than to front seats that fail adequately to support lanky thighs. Thanks to a long, cabin- extending wheelbase, legroom in the back is generous. So is the boot, which can be enlarged in the usual hatchback way by folding the split rear seats. Because the suspension maintains a constant ride height, heavy loads do not cause tail sag.

The Xantia's finish is much better than that of the plasticky old BX. Reflecting its high price, the VSX is also very well equipped. Anti-lock brakes (but not air bags) are included. So are power operation for the front and back windows, sun roof, mirrors and remote-control locks. The diesels do not have the keypad security system that immobilises petrol models until the correct PIN number has been tapped in. They do, however, get PSA's excellent fingertip radio controls, recessed into the steering wheel so you can keep your eyes on the road. Options include air conditioning and powered front seats but not, on the diesels, automatic transmission.

Specifications

Citroen Xantia TD SVX, pounds 15,995 (TD prices start at pounds 13,295). Engine: 1.9-litre turbo diesel, 92bhp at 4000rpm. Transmission: five-speed manual gearbox, front-wheel drive. Performance: 0-60mph in 11.5 seconds, top speed 111 mph, fuel consumption 35-45mpg on derv.

Comparisons

Audi 80TDi, pounds 15,756. Very economical (more than 70mpg at 56mph) and 'greener' than the Citroen, but slower and less refined. Technically advanced cat-cleaned engine sounds harsh and noisy. Solid, roomy, safe - but bland.

Ford Mondeo 1.8TD GLX, pounds 13,155. Ford's new turbo-diesel vies with Xantia 1.9TD LX on price. If the petrol Mondeos are anything to go by, this as-yet-untried car will be competitive for comfort, ride, handling and driver appeal.

Peugeot 405 STDT 1.9, pounds 16,066 (GR turbo-diesel pounds 13,440). Another cracking French diesel powered by the same turbocharged engine as the Xantia. Refined and nippy but not as economical as the Audi. Excellent ride and handling, comfortable and lavishly-equipped cabin.

Vauxhall Cavalier CD TD five-door, pounds 15,295 (GLS TD pounds 13,020). Rough and noisy 1.7-litre turbocharged Japanese Isuzu engine. Performance is quite strong, economy better than Citroen's but ride and handling lack composure.

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