Price: from £9,950 (range starts at £8,895, five-door version follows in January)
Engine: 1,390cc, four cylinders, 16 valves, 98bhp at 5,700rpm, 94lb ft at 4,250rpm
Transmission: five-speed gearbox, front-wheel drive
Performance: 140mph, 0 to 60mph in 11.3 seconds, 42.8mpg official average
CO2: 158g/km

You wait for years, then four come along at once. Not buses but superminis, even though they're not very mini any more. We've had the new Punto, the longest of them all. We'll shortly have Toyota's new Yaris and Peugeot's 207. And now, meet the new Renault Clio, another car that confirms the growth trend of once-downsize cars.

It seems extraordinary that a so-called supermini should seat four full-size people with ease and weigh, in its heaviest version, 1.2 tons. But people are getting bigger, and they want more from their cars: the ability to zoom up and down motorways, to hold a holiday's-worth of luggage, to protect them better in a crash. So cars are growing more corpulent, to the extent that today's Clio is almost the size of the old Mégane.

You can feel the difference as soon as you sit inside this third-generation Clio. It's a quality car in miniature, especially if it's above the two lower trim levels because it will have an expensively padded dashboard made from a large, single-piece "slush" moulding. Everything fits together neatly, textures are comfortingly tactile, the interior door handles operate with a smooth, light click. My driving partner did break off the steering reach and rake adjuster, but it's unlikely to be a regular failing.

Sit in the back, and you'll have headroom to spare. Legroom, too (as long as you and the person in front aren't giants), thanks to a wheelbase that's grown by 10cm. There's 33 litres more of luggage space, but against that the rear seats don't fold fully flat and there's an intrusive bracing bar between the rear wheel housings.

The glove box is genuinely capacious, and the middle of the rear seat is optimally shaped for children who can (optionally) have a headrest designed to hold the head in place when its owner is asleep.

Now stand back from the Clio and see the turn car design is taking. The "face" is recognisably from the current Renault design school with its two-part grille between huge headlamp covers, but the two parts are less prominent and no longer dominate; the eye is drawn instead to the air intake below the bumper. It will be even more so in next year's 200bhp Clio Renaultsport version, which will have subtly pumped-out flanks and an air diffuser under the back bumper. Even the gentler Clios come with one of two bulginesses of (plastic) front wing, according to wheel width.

Concept sketches showed a tail end much like that of the ass-shakin' Mégane, but the reality is less radical. It's still neat, though, and is the termination of an edgy, wedgy side-elevation. As expected, the bonnet and front wings are tall and bulbous to meet pedestrian protection regs, and the surprisingly spindly wipers hide behind the bonnet's rear edge, reducing wind noise. As expected of a Renault, the Clio has scored a five-star EuroNCAP crash test rating; one reason why this Clio has gained 133kg over the last one. It scores the maximum four stars for child occupant safety, too.

Underneath are some familiar mechanical parts. The structure and suspension are shared with the current Nissan Micra - Renault and Nissan are " alliance partners" - and, along with the engine range, with the Modus tiny-MPV. The forthcoming 140bhp, 2.0-litre Clio, in luxurious Initiale trim, uses a Nissan engine too, but the Sport Clio has a further-tuned version of the old-model Clio Sport's 2.0-litre motor. That extra power is needed to shift the extra weight, and the other engines in the range have also been boosted to suit.

Most impressive of the Clios I drove on the launch was the most powerful of the 1.5-litre diesels. This engine comes with 68, 86 or 106bhp, with torque of 118lb ft in the weediest version, 177lb ft in the beefiest. It seems extraordinary that one little diesel engine can have such a spread of potential outputs, and even stranger that the CO2 emissions figure (123g/km) is identical for both 68 and 106bhp editions. Why bother with the 68bhp one at all?

Anyway, the 106bhp Clio dCi, sampled in Dynamique trim with a sportily dark décor and optional keyless starting system, is terrific. This is how modern diesels should be: smooth, crisp in response, strong on pulling power. It feels like a 2.0-litre, with only a tardy build-up of boost pressure when accelerating from low speeds to betray the diminutive capacity. There's a six-speed gearbox, with a particularly easy, slop-free shift; other manual Clios, so far, make do with a five-speeder.

And with all this goes remarkable refinement. The engine is audible but never intrusive, there are no nasty resonances, nothing squeaks or rattles. The only spurious audio input is from the electric power steering, which occasionally moans like a disgruntled dog. Think of it as adding character.

The 86bhp diesel is still engagingly frisky and has a CO2 figure of just 117g/km. And the petrol Clios? They start with a 75bhp 1.2, which finds the new car's bulk hard work to move. Better go for the 98bhp 1.4, the core car, which has enough go to give the Clio the perky feel a small car should have. However, in another odd twist, the 111bhp 1.6 with variable valve timing has the same official "combined" mpg and CO2 figures as the 1.4, while feeling keener on the road. In Dynamique S trim, with wider wings and wheels, it's a sporty little hatchback.

But does this extra weight spoil the agility and flickability a small car should have? After all, if a small car isn't fun to drive, it has failed.

I'm pleased to say that the Clio passes the test. Yes, its power steering feels a bit glutinous if you rush it, but let it flow and you'll find it positive and solid, even if it's short on true road feel. But where the Clio scores is in its keenness to hook into a corner and stay on line, front wheels clinging, tail able to point the nose more tightly if you decelerate but without upsetting stability. It disguises its mass very well

The Clio soaks up bumps tidily and quietly thanks to good road-noise insulation and dampers. It really is a very refined, sophisticated little car. The best of the current crop? Undoubtedly - and it sets a new standard.

The rivals

NISSAN MICRA 1.4SE
£9,750

The Nissan Micra was the first car to be built on the platform shared with the Clio. This fantastic UK-made vehicle is engagingly curvy, and its 88bhp, 1.4-litre engine is smoother than it was. Despite all this, the Clio feels keener.

FORD FIESTA 1.4 ZETEC
£9,795

Square and soberly styled, the Fiesta is functional but hardly exciting. It delivers just 80bhp and inside is covered with a hard, plasticky trim (although this is about to be improved). Detailing aside, though, it is good fun to drive.

FIAT PUNTO 1.4
£9,800 (APPROX.)

On sale in February, the new Fiat Punto has a long, Maserati-like nose and lots of space for carrying luggage. But the 1.4-litre engine produces a measly 77bhp and the Renault beats it hands down for refinement and pace.