Arjeplog, Sweden - They do things differently in Arjeplog. In most parts of northwest Sweden, the landscape is shrouded in an eerie silence from late autumn onwards, but when the days are very short and the nights bitterly cold, this remote settlement near the Arctic Circle suddenly comes to life.

Aircraft from all over the globe touch down on the runway in neighbouring Arvidsjaur and the streets bustle with activity. From October to April every year, Arjeplog is the world's winter testing capital for carmakers who need to put top-secret prototype vehicles through their paces before regular production starts.

The region is dominated by high pressure systems of northern Russia and good winter conditions are more or less guaranteed from November to April. Most of the cars seen here are heavily disguised with strips of black tape or plastic slabs to prevent spy shots of the vehicles being taken before they are officially unveiled to the public at automobile shows.

"Conditions up here are ideal for us," said Wilhelm Cordes who is in charge of a test centre in Arjeplog run by German manufacturer BMW. The temperatures are suitably chilly, the lakes are deep-frozen and the road conditions are varied, with all the right combinations of ice, snow and abrasive surfaces.

"That is why there is hardly a single manufacturer or component supplier who is not testing around these parts," said Cordes.

For Mercedes developer, Stefan Hache, conditions are just fine for adjusting a car's all-wheel drive hardware, ABS braking ability and electronic stability programme. Hache was in Arjeplog last year with the Mercedes CL 500 4Matic.

Most of the testing took place on handling tracks laid out by the experts on frozen lakes in the locality. Mercedes and other carmakers maintain their own test centres, with a range of different tracks to simulate intense winter conditions. Facilities include tests with heated asphalt or ice, bumpy stair tracks and garages which can be cooled down to extremely low temperatures along with workshops.

The skills of the so-called icemakers are a key attraction at Arjeplog. A number of specialized firms began preparing ice circuits here
30 years ago and the car companies were soon queuing up to use them. Every morning from 4 am onwards, anything up to 100 warmly wrapped-up experts are on hand to unroll the white carpet for the test drivers.

"For us ice is not simply ice," said icemaker Mattias Jonsson who explains that carmakers want the ice customized to meet their needs.

The ice surfaces are brushed, polished or ploughed up with tracked vehicles to suit. Sometimes the icemaker cuts tiny grooves into the surface, adds water from the side to cut friction or sprinkles sand or salt to boost traction. When need be, Jonsson and his colleagues can also supply a fresh fall of snow. "Loose or hard-packed? Just let us know and we'll deliver."

"Being able to create winter conditions under exact laboratory conditions is a big help when it comes to programming handling systems," said BMW test driver Christian Thalmeier as he ploughs through the snow in a barely-recognizable 7 series limousine.

"Normal winter conditions on local roads are just as important though," adds the expert and the prototype limousine is taken out every day to cover an identical route. As the debut date draws nearer, attention turns to how the car performs in ordinary, everyday use.

"You could say we adopt the role of the very first customers with a particularly critical eye to how the new car performs, said his colleague Oliver Jung.

By this stage, it is already too late to change fundamental components of the car such as the type of seats used but some things can be changed at the last minute.

"We can alter the software parameters at very short notice," said Hache. That is why each test centre has a direct link with the car company's development department. Engineers with laptops can sometimes be seen at the roadside, making minor modifications on the fly.

Arjeplog is so popular with car makers that casual bystanders are apt to see more prototypes driving around than standard cars. One of the reasons is the filling station run by Per-Erik Granberg which is frequently besieged by photographers on the look-out for "scoops" of new models which they can sell to the car magazines.

"This is where all of us have to show our true colours. As soon as we refuel you can forget all the camouflage," said Mercedes developer Hache.

The activity keeps Granberg busy. "Instead of the usual 5,000 litres, I often sell between 8,000 and 10,000 litres of fuel a day," said the owner who complains though that photojournalists can sometimes be bad for business.

"If one of them has the place staked out, the testers just drive straight past." They inevitably come back since there are only two petrol stations in Arjeplog both opposite each other.

The roads around Arjeplog are uncommonly busy, but whereas other local government officials would be clamouring for measures to tame the traffic, mayor Bengt-Urban Fransson is grateful to the car testers. The presence of so many eligible men from out of town has been known to strain a few marriages and local bachelors often find themselves outclassed.

Yet without the car industry the town would be a dreary spot in the back of beyond, says the official. As he speaks, he gazes at the modest shopping mall and row of bars which distinguish Arjeplog from many other nondescript small towns in northern Sweden.

Right after New Year's Day when the last planes operated by the Airline FlyCar, a specialized carrier set up in 1999 just to transport cars and their testers, have landed, the population of 2,000 inhabitants is swollen by just as many drivers, engineers and developers.

"The testing industry provides the town coffers with 450 million Swedish crowns (54 million dollars) a year," said the mayor, gleefully recounting the long supermarket queues and booked-out hotel beds which indicate the boom. Local tradesmen also benefit greatly from the influx.

"Without the prototype circus and its entourage we could shut down the whole place and go home," said Fransson. (dpa)