SPY PICS: Next Skoda Fabia disguised as Volkswagen Polo

Late-stage testing of the all-new Skoda Fabia is already well underway ahead of the fourth-generation light hatchback's launch in early 2021 and, to prove it, our spy snappers have caught the pint-sized Czech testing high up in the Austrian Alps.

To throw the spies off, sneaky Skoda has disguised its baby hatch as the current Volkswagen Polo.

That makes sense as the VW Polo will again share much with the fourth-generation Skoda Fabia.

The big news is the Fabia finally ditches the aging PQ26 platform for the Volkswagen Group's latest MQB A0 architecture, which was well as underpinning the Volkswagen Polo also forms the basis of the Audi A1 and the Spanish SEAT Ibiza not sold Down Under.

The same platform underpins the larger Skoda Scala hatch that is also expected to donate many of its design cues to the Fabia.

Obviously, since the Skoda is dressed up as a Polo it's difficult to judge the Fabia's styling, but the camouflaged front end and visible air intakes suggest the Fabia will adopt the Scala's 'air curtain' front intakes.

The air curtains are designed to vent air around the front wheels to minimise the wake generated behind the front wheels, reducing drag.

The move to the MQB A0 is important as it will allow the Czech car-maker to introduce electrified mild-hybrid powertrains as well as semi-autonomous driving aids like the Volkswagen Group's latest adaptive cruise control.

More good news for Fabia buyers is that the MQB A0 will feature a longer wheelbase than the current model, maximising space within the cabin.

With fractionally more generous proportions to the VW Polo, expect the Skoda city car to lead the class for not only passenger space but luggage-carrying capacity.

More aero innovations could see the Fabia boast a low drag co-efficient which bodes well for efficiency.

Speaking of which, under the bonnet the Fabia will be powered by a range of small efficient petrol and diesels that will kick off with the 1.0-litre three-cylinder petrol that will produce either 48kW or 55kW and be combined with a five-speed manual transmission.

A more powerful direct-injection version of the small turbo 1.0-litre will offer 70kW or 85kW, with the latter set to be combined with either a six-speed manual or seven-speed dual-clutch auto.

The most powerful Fabias will come equipped with a 1.5-litre turbocharged four-cylinder that features cylinder-on-demand tech and later could be offered with a mild-hybrid system for even greater efficiency.

Just one diesel will be available – a 1.6-litre four-cylinder turbo-diesel that will get either 59kW or 70kW.

Inside, new technology will dominate the Fabia cabin, with the Skoda supermini set to adopt an 8.0-, or 9.2-inch version of the Mark 8 VW Golf's button-minimising infotainment system, while models with the DSG transmission will get the option of active cruise control that can cope with stop-and-go traffic.

Blind spot detection, rear cross traffic alert, plus a semi-autonomous parking aid will all be available.

There's no official word when the all-new Skoda Fabia will be introduced, but since the last-gen Fabia arrived in late 2014, it suggests its replacement will touch down in the second half of 2021 to fit in with Skoda's lifecycles.