WASHINGTON, May 14 (UPI) -- The Smart Fortwo, the smallest car for sale in the United States, scored well in safety tests, the Insurance Institute for Highway Safety reported Wednesday.

The Fortwo, smaller than minicars, weighs about 1,800 pounds and is more than three feet shorter than the Mini Cooper, the Institute reported.

It weighs in at one-third the weight of a BMW X5.

But, "the big question … how safe is it?" Institute president Adrian Lund asked.

"Among the smallest cars, the engineers of the Smart did their homework," Lund said.

The diminutive two-seater earned top ratings for front and side crashes and acceptable ratings -- the second best rating -- for protection against rear impact whiplash, the report said.

The report said the Smart car makes up for its small "front-end crush zone," which typically absorbs crash impacts, with a restraint system that "does more of the work."

It also has "a stiff side structure and standard side airbags," the report said. In side-crash tests "injury forces recorded on the driver dummy's head, neck, torso, pelvis, and left leg all were low."

"However, the driver door unlatched during the crash," the Institute reported.