PORTLAND, Ore.

BRINGING vintage cars to the parks, estates and golf course fairways where they can flaunt their beauty and compete for honors in the summer’s many concours d’élégance events is a well-rehearsed process.

But as museums have assembled more exhibitions that showcase the artistry and historical significance of automobiles, the task of putting vehicles into public spaces — often in the center of a busy city — has become infinitely more complex. Cars, especially prewar classics, can be huge. And while museums are accustomed to dealing with large artworks, the vehicles present challenges on another scale entirely.

Placing 16 cars inside the Portland Art Museum for the “Allure of the Automobile” exhibition, which opens this weekend, has been the job of Donald Urquhart, director of collections management for the museum....