Why So Many Supercars Have Montana License Plates

A legal loophole lets owners of expensive cars avoid taxes and emissions standards in other states. Tightening rules could send the practice into overdrive. 

A Montana vanity license plate. 

Photographer: Joe Sohm/Visions of America/Universal Images Group Editorial

The 1987 Porsche 911 that sold on Bring a Trailer on July 26 was a coupe so dreamy that late founder Ferdinand Porsche would be sorry to have missed it. Its diamond blue metallic paint—a hue so subtle that at some angles, it looked lavender—and throaty 3.3-liter flat-six engine were enough to bring $141,000 and more than 120 comments on its listing.

Close observers would also have noticed a detail far more polarizing than the semi-lavender paint job: The Turbo came with “a clean Montana title in the name of the seller’s LLC,” the listing said.