I would agree. I'm probably a lot older than you and I know my older brother and almost all of his friends had volkswagon's in the late 60's. I hated riding in one, felt like I was on the ground and semi's terrified me.
I honestly believe it's her boyfriend. I think it was almost too up close and personal to be someone she didn't know.
Three of the zodiac victims were shot which is somewhat impersonal and the stabbing of Hartnell and Shepard, he tied them up before stabbing, Cheri fought hard for her life and some of the DNA, I believe was under her fingernails and they believe the watch found nearby was also the killer. He didn't disable any of their cars and why would he do that to Cheri's if he was just looking for a victim, they were on a campus and there must have been a lot of people walking around alone. Instead of waiting for her to get into the car and find out it was disabled, wouldn't he have just grabbed her outside the car?
They think she walked away willingly with her killer. When she got out she would have been more likely to go with her ex boyfriend instead of a total stranger. They didn't appear to have a bad relationship after she got engaged to her fiancee and I don't remember reading anywhere that she was afraid of him.
I suspect more of these high profile cases are being checked for DNA but they're not telling so as to not spook the killer if he's still alive.