FIVE-HUNDRED feet beneath the earth's surface, Britain's motoring press was introduced to the latest car from Mercedes-Benz.

In what was possibly the most unusual media launch ever attempted by a car company, journalists assembled in a cavernous chamber of a salt mine somewhere beneath the "footballer belt" of Cheshire, where they know a thing or two about premium class cars but, like me, probably very little about salt mining.

The test route along the wide corridors of Winsford Salt Mine, which supplies much of the gritting salt for our roads, was hardly challenging for a car with the four-wheel-drive capability of the new GLA-Class. Roof-mounted headlamps pierced the darkness to reveal some roadways with ice-like polished surfaces and others that were mere dirt tracks.

There's a network of more than 130 miles of tunnels down there stretching 5km east to west and 3km north to south, so there was never any danger of running out of road.

But I was left asking myself whether the owner of a new GLA-Class would care to take their pride and joy along more challenging roads above ground, and the answer is probably not.

The GLA-Class is a chunky evolvement of the A-Class and rounds off the company's extensive SUV portfolio, providing an alternative to the BMW X1 and Audi Q3.

The first Mercedes-Benz car in the fast-growing compact SUV segment comes with the option of the new-generation permanent all-wheel drive system 4MATIC for those who want the reassurance of a full-blooded four-wheel drive system or a straightforward two-wheel drive set-up.

Whichever option is chosen, you get a comfortable ride in the GLA, which a tad longer and taller than the A-Class.

The driver benefits from a raised position, yet it feels very much like a regular A-Class to drive. Yes, you do lose a little agility, but the truth is that it is barely noticeable.

There's a choice of two diesel engines. The 200 CDI develops 136 hp and maximum torque of 300 Nm and has a displacement of 2.2 litres. It emits only 119 g CO2 per kilometre, while the 220 CDI 4matic has a displacement of 2.2 litres, develops 170 hp and emits 132g/km of CO2.

The petrol version is the 250 4matic, utilising a two-litre engine that develops 211hp and emits 154 g/km.

In June, the range of engines will expand to include a 45 AMG with a two-litre turbocharged engine that will be the most powerful series-production four-cylinder turbo engine in the world.

It's the diesels that will find most homes, and it's worth stretching to the more powerful version for a more satisfying drive. The lower-powered model will suit most needs, and is smooth and quiet, but its big brother steals the show as the best all-rounder.

Strangely enough, despite the car being taller than the A-Class it is not particularly easy for a six-footer to clamber in and out, but once settled into the driver's seat there is an immediate sense of wellbeing.

There are two equipment grades, SE and AMG Line, which adds £1,000 to the price tag. Both models come with DAB digital radio, a reversing camera, air-conditioning, automatic wipers, privacy glass and a 5.8-inch multimedia display. The media interface includes Bluetooth ’phone connectivity, a USB port to connect an mp3 player to the stereo and an Apple connector cable for iPhones and iPods.

SE models come with a softer ‘Comfort’ suspension set-up whereas AMG Line versions get Sports suspension and more responsive power steering, plus lots of cosmetic touches.

High-grade materials in SE or AMG Line abound, the detailing is exquisite and there's a dynamism about the design. Top marks then for the cabin.

The dashboard, which consists of an upper and lower section, features five round integrated air vents with optional bezels, while the three-spoke steering wheel is equipped with 12 function keys and a galvanised chrome clasp.

It might be longer, but the GLA feels no bigger than the A-Class inside. But that extra length (4,417mm against 4292) equates to a significant increase in boot capacity (up from 341 litres to 481)

If the optional load compartment package is ordered, the backrest of the rear seat unit can be moved to a steeper position, the so-called cargo position. This enlarges the load compartment capacity by 60 litres, providing space for bulky items while still allowing the rear seats to be used by passengers.

The lower-powered diesel GLA can achieve combined fuel economy of more than 60mpg, while the petrol GLA 250 4matic sprints from zero to 62 mph in only 6.5 seconds, and the GLA 220 provides figures nestling between the two.

The GLA's primary role is to fit perfectly into the day-to-day urban lifestyle, but with the optional 4matic all-wheel drive, it will traverse a beach, loose ground or unsurfaced gradients. Even if that unsurfaced gradient is 500 feet underground.

Prices start from £25,080 for the GLA 200 CDI.

At a glance

Mercedes-Benz GLA 220 CDI SE

Price: £29,235

Engine: 2.2-litre diesel developing 170bhp

Transmission: Seven-speed automatic driving all four wheels

Performance: 0 to 62mph in 8.3 seconds; top speed 134mph

Economy: 55.4mpg combined

CO2 emissions: 132g/km