Two Clio road tests quite close together isn't a case of over-egging the pudding, because the previous report was on a three-door petrol-engined Dynamique, while this is a five-door (and better-looking) Expression with the very latest common-rail turbo diesel.Until recently, you couldn't get a diesel engine much below 1.9 litres in capacity. But now Renault has slipped in the 1.5-litre dCi, just before the Peugeot/Ford 1.4-litre, under a variety of names, makes its showroom appearance.So the day of the small-capacity turbo diesel has dawned, although not, as far as actual production of the dCi units is concerned, in France. Renault has invested around £85 million in its engine factory at Valladolid in Spain, which has a planned capacity of 7500 of these units per week.As with so many engines these days, the dCi is a combined effort. Renault's technical partners in the project include Delphi for fuel injection, Teksid, Federal Mogul, Melco and Borg Warner, which contributes the turbochargers. There are two different power outputs, 65PS and 80PS according to Continental measurements, and a little less UK-style. The intercooled 80PS engine arrives here next year.Both versions are frugal on fuel and as clean as they can be, and the entry-level engine as fitted to the test car makes the Clio go pretty well for something with such a modest power output. It's a strong hillclimber, and if you hit the sweet spot on the torque curve, which reaches 118lb/ft at 2000rpm, it overtakes unexpectedly briskly.It does all this with very low on-the-move noise levels. That's mainly because of the careful design of the second-generation, lightweight low-friction common-rail engine, with the vibration sensor which allows self-adjustment of each injector, but the removable acoustic cover under the bonnet plays its part too.Anything able to offer an extra urban fuel consumption of more than 75mpg and a rock-bottom CO2 emission figure below 120g/km is welcome. A lot of people with modest budgets to run company cars will be looking at vehicles like this, in which the all but unjustifiable 3% diesel surcharge won't make much difference.Even with the lower-powered engine, the dCi Clio is pretty lively, with light handling to make it nippy in town and out on the open road. The slick gearchange and electric power-assisted steering help, and there's very little of the nose-heavy effect which dulls the handling of some bigger-engined diesels.Naturally, most of the dCi's equipment and layout is shared with the petrol version. I still don't like the left-biased wipers, although there's nothing to be done about them, and I don't think the latest twin-cowled instrument display is an improvement.The Clio has a pleasant front cabin, with restricted legroom in the rear because, although it has been updated, it sits on a shorter platform than some of its upcoming rivals. I thought the boot was fair enough, though, by current supermini standards.The Expression has the same multiplex wiring as the rest of the range, which means "intelligent" wipers and various other odds and ends. It's the grade above the entry-level Authentique, with heated door mirrors, a height-adjustable driver's seat, a split/fold rear seat, a six-speaker sound system, an outside temperature display, a front map-reading light and a tilt/remove sunroof, alas with no shutter.I'm quite sure that small-capacity diesels will really take on, once people realise what advantages they offer, and here we have Renault leading the field. If you don't object to the looks of the three-door, it costs £500 less.Second opinion: A very fine little diesel motor which gives the Clio more than adequate performance. And strangely enough, this is possibly the nicest-handling present-day Clio I've driven - it's certainly the one with the most compliant ride, in the true French style, though without a trace of wallow. The big problem is still the restricted rear room, which knocks the car out of contention as a method of transport of four adults. David Finlay. Engine 1461cc, 4 cylinders Power 63bhp Transmission 5-speed manual Fuel/CO2 65.7mpg / 115g/km Acceleration 0-62mph: 15.0 seconds Top speed 100mph Price £9195 Details correct at publication date