Petra Verkaik, a 22-year-old native Californian, celebrated the signing of her Playmate contract in an unusual fashion: by running herself over with her own van. The venerable '76 Volkswagen has a habit of not starting, so Petra's accustomed to climbing under the chassis, armed with a screwdriver, to get things going. This time, in her excitement about becoming a Playmate, she neglected to check whether or not the transmission was in gear. When the motor turned over, the van lurched onto her chest and perched there for about 30 seconds. "A very long thirty seconds," she says. "I thought I was going to die." With a mighty effort -- "I'm not Hercules or anything, but it's a light car" - Petra managed to free herself, sort of. "I pushed it up and slid under it. Then it landed on my hair, pinning me." Fortunately, the episode took place in the parking lot next to Playboy's West Coast offices, and rescue was soon at hand. Cassie Gould, a Playboy publicist, was the first to happen by and see two legs sticking out from beneath the dilapidated van. Her call for help was answered by two security who quickly got the van off the Playmate; paramedics and sheriff's officers arrived seconds later. At the hospital, Petra was X-rayed and got the good news that she could go home immediately. The bad news was that now that Petra was obviously out of danger, everybody was cracking jokes about the accident. When a Playmate, particularly a well-endowed Playmate, is saved from serious injury by her breasts, people smile. It's not unlike the story of a preacher's being saved from a stray bullet by his Bible. And Petra is by nature a rather shy person. "God, I was so embarrassed," she recalls. Still, when she heard that West Coast Photo Editor Marilyn Grabowski had dubbed her the "the retread Playmate," Petra good-naturedly responded, "Well, I did have tread marks on my shirt. What else can I do but laugh?" Petra and her misbehaving van go way back. "My mom bought it new, and we used it to camp at the Grand Canyon and everywhere." Last year, her mother gave Petra the van. Since then, its trips have most often been to the mechanic. Still, it has provided reliable-enough transportation to get Petra to modeling assignments (she recently did some promotional work for Pepsi). She currently shares a house near L.A. with three others, including her boyfriend, with whom she pots fantasy travel plans (first stop: Bali, her mother's birthplace; her father comes from Holland). Her next move, however, may be to try out for a spot in Playboy's Girls of Rock & Roll review, currently in Las Vegas and Lake Tahoe. "Playboy has helped me a lot," says Petra. "It has given me self-confidence. Now I love meeting people." There's another plus: With her Playmate earnings, she'll be able to buy a new car. "Something light," she says, smiling. "Like a Honda CRX."