WASHINGTON - Consumers Union's controversial rollover-propensity test involves a rapid double lane change designed to simulate an emergency avoidance maneuver.
It consists of a swerve to the left, a swerve back to the right and an attempt to straighten out.
Consumers Union says the test represents an emergency situation a motorist might encounter in daily driving, such as trying to avoid a child running into the street.
'It is not a stunt,' said David Pittle, Consumers Union's vice president and technical director.
There are two versions: One is conducted on the long course, and the other on the short course. But total distance covered is the same in each: 240 feet.
The short course is more demanding of a vehicle because the first turn to the left is made in a shorter span, 50 feet instead of 60 feet in the long course. Also, the pylon representing the obstacle being avoided is set 3 feet farther left in the short course.
'It represents what an inexperienced driver would do' in an emergency, said David Champion, Consumers Union's auto testing director.
That is, the inexperienced driver would steer too far and too abruptly to the left and, on the return to the right lane, risk losing control or rolling over, he said.
Consumers Union puts all vehicles that it tests through the long course and bases its emergency-handling evaluations on the long course. Additionally, it puts compact pickups, minivans and sport-utilities through the short course to further test their stability limits, Champion said.
On each course, drivers take vehicles through the lane changes at increasingly faster speeds until they begin knocking pylons over - or in the case of a few vehicles, until they go up on two wheels.
Normally, vehicles complete the long course successfully at up to 55 mph and the short course at 35 to 45 mph.
In 1996, Consumers Union rated the Isuzu Trooper II as 'not acceptable' after testers said it went up on two wheels at 43 to 45 mph on the long course and at 33 mph on the short course. Isuzu has sued Consumers Union over the report.
FACTORS IN RATINGS
The National Highway Traffic Safety Administration, which is conducting research to find a reliable test for rollover propensity, has criticized the Consumers Union short course.
a Consumers Union petition for a defect investigation of the Isuzu Troop-er II, NHTSA said: 'The short course test, as conducted by CU, does not provide a sufficient scientific basis on which to determine the existence of a safety-related defect.'
The emergency avoidance maneuver is one of five factors that go into Consumers Union's emergency-handling ratings for vehicles. And emergency handling is just one of a series of categories in which Consumers Union rates vehicles.
Consumers Union tests each vehicle for several thousand miles and evaluates braking, acceleration, fuel consumption, comfort, interior noise, controls and displays, routine handling and emergency handling.
Factors in emergency handling include performance on a skid pad, steering feel, controllability, speed in the avoidance maneuver and driver confidence in the avoidance maneuver.