The agency said during crash testing in December the driver seat belt webbing completely separated, prompting the investigation into whether the issue could occur in consumer driving. A Volkswagen AG spokeswoman said Friday the Tiguan has performed well in other tests and the automaker "will fully cooperate with NHTSA in the investigation and work to identify the cause of the different results between NHTSA's and our internal testing." VW introduced the new longer, three-row Tiguan in the United States last year as it expands offerings of larger vehicles for American buyers.

(Reporting by David ShepardsonEditing by Chizu Nomiyama)