Federal safety officials have opened an investigation into the Saturn Vue after the suspension failed on two of the SUVs during recent government tests, causing the rear wheels to collapse.

The National Highway Traffic Safety Administration (NHTSA) said the agency had received a consumer complaint about a similar incident that led to a rollover. The suspension failures occurred as the agency was following up on that complaint.

The failures occurred on both a four-wheel-drive and a two-wheel-drive Vue. NHTSA said the four-wheel-drive vehicle's suspension failed at 45 miles per hour as it was being put through a series of sharp turns meant to resemble sudden swerves and accident avoidance maneuvers. It didn't say how fast the two-wheel-drive vehicle was going at the time of the failure.

NHTSA said only that it has opened a defect investigation, a process that can take a year or more and which can lead to a recall.

The Vue and other SUVs have been under heightened scrutiny because of the rising incidence of rollovers involving SUVs and pickups.

Consumer advocates pounced on the incident, calling on GM to launch an immediate recall. Clarence Ditlow of the Center for Auto Safety called it "truly amazing" that the same failure occurred in two vehicles, which he said was a clear indication of a design flaw.