I’VE NEVER SEEN the appeal of Peter Pan. He must always be asked for ID in pubs, and he can’t have paid off his student loan, let alone got on the housing ladder. But when some people mutter that a car has grown up, you get the sense they mean it negatively.

Well, Seat’s new Ibiza has grown up: it’s quieter, exudes VW Group quality and is stuffed to the gizzards with ‘big car’ technology. Not that it’s grown up physically: the Ibiza is actually a hair’s breadth shorter and lower than its predecessor. But there’s abundant space inside: a longer wheelbase ensures no contact with the driver’s seat for a six-foot backbencher, and a large stretch sideways means you won’t rub shoulders with your passenger. Indeed, the Ibiza is now only 90mm narrower than a Golf! This girth necessitates wider tracks, which help form the Ibiza’s dynamic character: this is one super-planted supermini. The front end clings to the road like Ed Sheeran to publicity, keeping understeer at bay, with a smidgen of body roll. Tip the Ibiza into a fast corner with the light, responsive and consistently weighted steering, and the roll builds progressively without getting ungainly. The overwhelming feeling is of a stable, well-sorted chassis.

And that’s good news, because the Ibiza is blooding a new VW Group platform - catchily titled MQB-A0 - that will be the backbone of squillions of cars, including the new VW Polo/ Audi A1/Skoda Fabia and a host of small crossovers too. Think of A0 as a shrunken version of the Golf class’s MQB platform, mirroring its transverse engine/front-wheel drive layout, and dimensional flexibility to underpin multiple brands’ cars. While posher MQB cars have a multi-link rear axle, the Ibiza’s is strictly torsion beam, with MacPherson struts up front. The Ibiza rides comfortably and quietly, although the mountain roads above Seat’s Barcelona HQ are paved with velvet.

The sporty FR trim has a unique sports suspension with a firmer setting, but - like the drive mode selector which adds a little steering heft and throttle sharpness - the gains are so marginal even Sir Dave Brailsford might not bother with them. On the motorway, there’s barely a rustle of wind, and the tyres produce just a gentle hum. Torsional rigidity improved by 30% has helped deliver these advances in refinement and driving precision, says Seat.

Petrol engines span 74bhp base model to 148bhp 1.5-litre, with a 94bhp or 113bhp turbocharged 1.0-litre triple in between. We drove the latter, coupled with an accurate six-speed manual. This 1.0 TSI requires plenty of cog-swapping faced with overtaking or inclines; its sweet spot is above 2000rpm, where it generates 148lb ft of torque. There’s a 1.6-litre diesel in various states of tune too.

MQB-A0’s new electronic platform supports some compelling technology. Ibiza FR, SE Tech and Xcellence models get a super-sharp 8in touchscreen, to control most functions including the standard navigation. The top two trims have Apple, Android and MirrorLink capability for safely operating smartphones, a driver tiredness monitor and Adaptive Cruise Control. Front Assist automatic braking is standard. Access to all that tech should satisfy the Ibiza’s customary audience: a youthful bunch barely older than Peter Pan.