What is it about Airstream design that continues to engender such passion more than 80 years after the trailer first appeared?

Is it the alluring, streamlined aluminum shell? The cozy interiors? The nostalgia for a simpler era?

“It’s a part of American culture that transcends time,” said architect Matthew Hofmann, 29, who recently opened an Airstream hotel consisting of four tricked-out trailers parked midtown at the Santa Barbara Auto Camp. “It symbolizes style and adventure. There is something very fundamental about getting in your car and driving across country. It’s in our blood.”

On a recent afternoon, curious pedestrians repeatedly interrupted Hofmann and business partner Neil Dipaola to ask if they could take a peek inside the trailers. Upon entering, they found renovated interiors with hotel upgrades perfectly suited for “glamping” — mini-bars, wall-mounted flat-screen TVs, air conditioning and 1,000-thread-count sheets, all for $150 per night.

According to Airstream, about 70 percent of all the trailers ever manufactured by the company are still in use, so it is not surprising that Hofmann, as well as other entrepreneurs, would think to use them as lodging.

Singer Kate Pierson of the B-52’s opened her second vintage Airstream hotel — six trailers near Joshua Tree, Calif. — in November.

But unlike Pierson’s playful kitschy decor (think the B-52’s “Love Shack” video), Hofmann’s Airstreams stand out for surprising elegance. The modern updates are no different from any home remodel, he said, and he viewed his trailers from the 1950s-70s as small-space living.

How to create an open and airy feel in just 150 to 200 square feet? Cut the excess, Hofmann said. “I tried to lighten them up and simplify them while maintaining their classicism,” he said.

The architect used a few tricks to give them visual flow. Because the four trailers are used as hotel rooms, not for extended traveling or permanent living, Hofmann reduced the amount of storage, which had made the interiors feel tight. Next he removed plastic accessories that created “visual noise,” such as window coverings, valances and spice racks. Vents on the roof were doubled in size to create sky- lights, bringing in sunshine.

“It’s more than just painting the walls white. It’s how the space feels as you move through it,” he said.

To add warmth, Hofmann installed strand bamboo and teak flooring. “You don’t want to feel like you’re in a tin can.”

Hofmann saved original shelving and all the windows.

The most surprising space in each Airstream is the bathroom, traditionally the size of a closet. Hofmann expanded them and created a sense of luxury with colorful recycled glass tile and wraparound Corian countertops. Full-size toilets are a plus. In one trailer, he even added a claw foot tub.

Hofmann has renovated more than 20 Airstreams and now focuses on renovating vintage trailers for more hotels. “It appeals to me because it is history, it’s American and, as a LEED architect, I can make it sustainable,” he said of the U.S. Green Building Council’s Leadership in Energy and Environmental Design program. Visit www.hofarc.com/new-airstream-hotel-in-santa-barbara.

Humorist Charles Phoenix, author of “Americana the Beautiful,” said the fascination with vintage Airstreams makes sense as each is a “cozy cabin on wheels that looks like a bright and shiny Twinkie. How could something so warm and cozy be so shiny and slick at the same time?”