Rich Rosenberg and three friends puttered toward Bryant Lake, their compact, brightly colored vehicles serving as motorized Pied Pipers. A car and motorcycle had been tailing them for miles. As they neared the shoreline, a group of gawkers gathered to watch as the odd little autos drove straight into the water.

Were they cars? Boats? Or what, exactly?

“It’s not a good boat and it’s not a good car,” Rosenberg said, “but it’s serviceable as both, just kind of gets you where you want to go.”

Actually, they’re amphibious automobiles called Amphicars, but long ago they earned the nickname “Smile-mobiles.” Whether they’re on land or sea, they rarely fail to evoke ear-to-ear grins.

“It’s amazing how many people have chased me down on the highway and pulled out cameras,” said Mark Mathiasen, a member of the St. Croix Valley Amphicar Club.

Even on solo sojourns, Rosenberg said, “you’re never alone in these cars.”

During the early ’60s, Amphicars were manufactured in Germany for the U.S. recreation market.

They were rising in popularity — more than 3,000 were shipped; even President Lyndon Johnson owned one — but they slipped into obscurity when the company that made them folded in 1965.

“It’s a great invention that unfortunately didn’t pan out,” Rosenberg said.

Still, they have a surprisingly loyal following here. Between Mathiasen’s club, which boasts nearly two dozen members, and Rosenberg’s informal group of friends, and several “up north” resorts, Minnesota has an outsized share of the nation’s 400 remaining Amphicars.

‘Humility on wheels’

A sense of humor isn’t a prerequisite for owning an Amphicar, but it doesn’t hurt. In addition to looking sort of silly, the vehicles, which have a rear-mounted, 43-horsepower Triumph Herald motor, are difficult to maintain.

And even though they max out at 7 miles per hour on water and 70 on land, they can be tricky to operate.

Drivers make the land-to-lake transition by switching on a watertight seal on the doors and, while rolling into the water, putting the transmission in neutral and engaging the two nylon propellers under the rear bumper. (The steering wheel works because the front wheels also serve as rudders.)

When coming back onto land, the key is putting the transmission back in gear so the wheels start turning. And hope that the engine hasn’t, uh, flooded.

“The big headline of this is you can’t take it too seriously,” said Robbie Soskin, Rosenberg’s running partner. “It’s humility on wheels.”

For Soskin, there’s more trepidation entering the water than leaving it. “Every time I go in, I say, ‘Float this time,’ ” he said.

His buddies still give Soskin grief about the trouble he got into “because I didn’t know about the bilge pump.”

But these guys have been known to fish from their vehicles and cook on the exhaust manifolds “just to mess with people,” Rosenberg said.

Rosenberg, whose Amphicar license plate reads “IFLOAT2,” couldn’t resist having fun from the get-go. In the first month he owned the Amphicar, he took a friend for a ride in what she thought was just a peculiar-looking convertible. “So we were headed towards a lake and I said, ‘The car salesman said that if I go real fast, I can get across the lake.’ I gunned it in and she jumped on top of me with high heels.”

On another occasion, Rosenberg and some buddies drove onto a St. Croix River island and around a campsite. The next day they returned to find some frightened campers. “They had come back the day before and saw the tire tracks and thought they were being attacked.”

Building and maintenance

The balky mechanics are one reason Amphicar owners tend to travel in groups.

“There’s safety in numbers,” said Carl Bretzke, one of Rosenberg’s cohorts.

And even with infrequent use, the 50-year-old vehicles need maintenance.

Because there’s just one parts dealer in the country, Soskin has devised another approach: “You pray, and you find a mechanic willing to learn,” he said.

One aficionado who has learned a lot is Duluth’s Tom Maruska, who recently started rebuilding his fourth Amphicar. To do so takes several months of daily work for the retiree.

“I take the car completely apart, 100 percent, and do all the work here except rebuilding the engine,” he said. Once finished, he typically hangs on to the car for a year or two before selling it.

While most Amphicars sell for $50,000 to $60,000, one of Maruska’s restorations went for $124,800 in 2006, still a world record, he said.

Even though Rosenberg argues that those prices aren’t unreasonable (“What’s a good car, a boat trailer and a good boat worth? Add it up.”), he admits it takes a certain kind of individual to want one.

Amphicar folks love being out on the water, but they’re not boat people. “You don’t want one if you live on a lake,” Soskin said, “because half the fun is driving there. We’re in a lot of people’s scrapbooks.”