The used Chrysler minivan came fully loaded, with power steering, foldaway seats, tinted windows — and half a million dollars’ worth of cocaine.

San Jose psychologist Charles Preston had no clue there was a cellophane-wrapped stash of “snow” hidden inside the frame when he bought the pristine-condition, 2008 van last year from Thrifty Car Sales in Santa Clara. True, the windows wouldn’t roll down all the way. But he had no reason to suspect it was because the door panels were crammed with kilos of coke.

He found out 15 months later when he went to a mechanic to get his brakes checked, and immediately turned the contraband over to police. Now, he’s terrified a drug cartel still may be gunning for it.

“People make jokes — oh, you should have sold it,” Preston said of the cocaine. “But honestly, I’ve never been so scared in my life, even when I was mugged in New York.”

San Jose police said Preston’s worries about the unusual discovery are warranted.

“It’s absolutely dangerous,” said Sgt. Jason Dwyer, a police spokesman. “If somebody is motivated to track down that van and doesn’t want any witnesses, then some physical harm could come to the owner. That’s a lot of dope to be misplaced.”

Preston bought the van in May 2010 for what he figured was a bargain — $14,000 in cash — and uses it to haul food he pays for out of his own salary to feed people living on the street.

The moment he drove the white van off the lot, he noticed the window on the driver’s side wouldn’t quite go down all the way and the passenger’s side window also stuck a little. But he figured he could live with it since the Town and Country van had an excellent air-conditioning system. He also said he’d never bought a used car before, so he didn’t realize he might have been able to bring it right back to the dealer for a free repair.

‘My hands went numb’

About 15 months later, in August, the brakes started making funny noises, so he brought the van to DHT Collision & Service Center in downtown San Jose to have it checked.

When he went to pick it up, one of the managers said he noticed the window problem and offered to check it out.

“This insulation isn’t supposed to be here,” the manager said, digging behind the panel. But it soon became clear that the tablet-sized objects wrapped in purple and clear cellophane weren’t installed by the manufacturer.

“I’m, like, dumbfounded,” said Preston, who works at Santa Clara Valley Medical Center. “Honest to God, my hands went numb.”

Police quickly arrived and found 14 packages of cocaine hidden in the doors. After impounding the van for closer examination, they found five more above the back wheels, Preston said.

“They told me, ‘You’re so lucky, you’d be in jail for the rest of your life if you got searched in a traffic stop and they found this.’ “

But they also told him something chilling: Take the van back in to the repair shop to check for tracking devices because somebody is probably looking for it. Then get rid of it.

When Preston tried to return the coke-mobile to Thrifty Car Sales this summer for one without drugs, he said a manager was anything but solicitous. She told him he could trade in the van, but only for the current Blue Book value — about $4,000 less by his estimation than he originally paid. He had put about 6,000 miles on the van.

Preston refused to take a loss on the vehicle.

“It took me a long time to save the $14,000 for the van,” he said. “I should get what I paid for it in trade-in value.”

Ron Battistella, the owner of Thrifty Car Sales, said that’s not what he wanted conveyed to Preston, and he’s now willing to replace the van with a drug-free ride.

Preston can’t wait.

“I just want to get rid of the van. I don’t want it in front of my house,” he said. “Somebody could just come and want the car and run me off the road. When I drive now, I’m always looking around.”

Origin unknown

Police have been unable to track down the cocaine’s history or identify the dealers. It previously had been owned by a rental car agency so it’s conceivable someone who rented it packed it with cocaine.

“The way it was packaged is indicative of a long-distance transport, perhaps across state lines or from Mexico to the U.S.,” Dwyer said. “It could even be from one side of town to the other, depending on how paranoid the dealers are. They might do that in the off chance they got pulled over.”

If there’s one silver lining, Preston said, it’s that the story could be an asset in social situations.

“When someone says, ‘Tell me about yourself,’ ” he said, “I’ll finally have something interesting to talk about.”

Contact Tracey Kaplan at 408-278-3482.