Pettersson said engineers stay for a week to a month. Any longer than a month gets to be monotonous, engineers said, because there is little to do besides work. Going out to eat can be tricky because there are not many restaurants, which means conversations need to steer away from work topics.
"Nobody wants to talk in case a rival's listening," said an engineer who asked to remain nameless. "Everyone looks to see what prototype you've driven to the car park. It's a really weird atmosphere."
Despite that, Arjeplog's environment with its reindeer forests, endlessly configurable lake tracks and occasional nighttime glimpses of the famed Northern Lights is a useful draw.
"It's not just about testing cars. We bring customers here, the press, the investors; this is about selling the technology of the group," GKN's Rickell said. "It's a nice, informal, friendly atmosphere. You don't wear a suit and tie. It's very different [from] a meeting in Germany."
Increasingly, auto companies using simulators or indoor facilities re-create some of Arjeplog's worst conditions. Scania, for example, has a climate-controlled wind tunnel that can replicate snow and bring the temperature down to minus 40 Fahrenheit, as well as simulate heat and high humidity. But as Scania's Pettersson said: "Not everything can be replicated in the tunnel."
The potential of these lakes was first discovered in 1969 by two adventurous engineers from Opel who had driven to the area from Germany. A team of Opel engineers returned four years later and swept a rudimentary track on Lake Hornavan with brooms.
The Arjeplog Times, a local newspaper produced only during the winter testing season, reported that those engineers had a unique way to make sure the ice was safe for a car. They put an Opel Admiral into drive, pointed it toward the lake and got out as it rolled away just in case it broke through. The ice held.
It wasn't long before others -- including the spy photographers -- joined Opel.