COLD REGIONS TEST CENTER, Alaska -- When Soldiers in Iraq and Afghanistan were imperiled by the destructive power of improvised explosive devices, a variant of the armored Stryker combat vehicle sporting a specially-designed blast-diffusing hull saved countless lives.

Particularly suited for transporting infantry in urban environments, the Stryker combat vehicle has become popular among Soldiers in the most dangerous and rugged areas overseas. They know the vehicle to be quiet, reliable, and easy to maintain and repair.

The vehicle's stellar performance is doubtless related to the extensive evaluation it has undergone at Yuma Proving Ground and its three subsidiary test centers since 2002, including a six month stint in the jungles of Suriname in 2008. Earlier this year, a new variant of the vehicle wrapped up a winter of extreme use at the Army Cold Regions Test Center.

Boasting an upgraded chassis and drivetrain along with a variety of mechanical, electrical and digital improvements to enhance its performance, the latest Stryker variant was subjected to more than 3,000 miles driving across rugged terrain in extreme cold.

"It looks like a regular Stryker, but it isn't," said Richard Reiser, test officer. "It has a larger engine that significantly increases horsepower and torque. It has a much greater diagnostic capability that integrates subsystems. This gives operators a greater awareness of vehicle health and potentially improves situational awareness during the actual mission in the vehicle."

In the world's most frigid environments, cold starts can be harrowing even for the most rudimentary vehicles. For a complex system like the Stryker, each component's ability to function in extreme cold is crucially important and was subjected to keen evaluation in temperatures far below freezing.

"Like automotive trends in general, we have much greater reliance on computer systems in these vehicles," said Reiser. "Those computer systems and subsystems integrated into the hull depend on a great deal of computer software and hardware."

Though a vehicle's performance characteristics are similar in cold weather once a vehicle is started and sufficiently warmed up, dramatic fluctuations in temperature can degrade performance of any number of a vehicle's components.

"Stopping distance and acceleration shouldn't change profoundly in this environment," explained Reiser. "The real issues tend to be related to rapid temperature differentials. Each sub-zero temperature threshold tends to flush out small anomalies."

Testers went to great lengths to test in potential failure conditions. For example, after a long drive on the range the day before a particularly nasty drop in temperature was forecast, the testers used fans connected to long tubes snaking into the engine compartment and other vital areas of the vehicle to blow frigid air onto the components overnight.

"We adjust to capture things and be ready for those colder temperatures on short notice," said Reiser. "It's a small crew and it's easy to make adjustments to the mission profile to take advantage."

Throughout the test, the Army evaluators used the same vehicle that had been subjected to punishing hot weather testing the previous summer at Yuma Test Center, Arizona. Personnel travelled to Yuma to take part in the testing and instrumented the vehicle in a configuration that applied to testing in both climates.

"It provides not only continuity in the instrumentation process, but helped our technician get it done quicker while supporting Yuma's effort as well," said Reiser.

The test was more than just endless driving. The performances of every special feature the vehicle boasts were scrutinized, from its communications suite to the central tire inflation system that adjusts tire pressure as the vehicle is in motion.

"Cross country miles accumulate slowly in this environment," said Reiser. "We didn't have consistently cold weather, so we were able to move what sub-test activity we were doing based on its environmental relevance. If it is something that's not so much impacted by extreme cold, we moved that to the less-cold times."

Soldiers from Fort Wainwright's 25th Infantry Division also assisted in the testing by entering and exiting hatches of the vehicle while attired in the full complement of armor and Arctic battle dress, ensuring that everything in the vehicle could be reached without snagging their bulky gear.

"It was great coordination between the two tests to pick the appropriate miserable day to get the Soldiers to do some limited ingress-egress testing," said Reiser. "When this vehicle is fielded and the Soldiers have the new body armor, we'll already know it isn't an issue for ingress and egress."

The multi-month test was completed ahead of schedule and under budget, which Reiser attributes to the flexibility of the rugged, self-contained six-person crew. The drivers, for instance, were from the testing center's maintenance shop. They were able to troubleshoot and repair problems that cropped up without lengthy downtime at a maintenance shop many miles from the test range.

"We were able to eliminate delay times when we went into maintenance because maintenance was right here," said Reiser. "If we had a vehicle issue, they just changed hats and researched from a different vantage point what they had to do to solve the problem, which was a huge cost savings."