Just what kind of person would go undercover to market products without telling unwitting targets what they’re doing?

It could be anyone, really. Your neighbor. A relative. Your best friend. As long as the "agent" is enthusiastic about what he or she is hyping.

One 29-year-old New York City doctor, who requested anonymity, said he drove Audi A8 cars around cities in Germany at night for six weeks when he worked at a promotion company three years ago.

The car company solicited him and six male models to drive around Frankfurt, Munich and other places in the A8s wearing sharp suits courtesy of Audi, with beautiful female models as their passengers.

"Audi paid for everything — our meals, drinks and extra clothes," he said. "Audi considered it a promotion."

The auto manufacturer went to such lengths to market the launch of the A8, a new luxury auto, he explained. During the day the promotion campaign was more overt, marked by visits in the cars to Audi and other dealerships.

A spokeswoman from Audi of America did not return calls seeking comment.

"If you see people in their 20s driving very expensive cars with good-looking girls, you’re probably going to turn around," said the doctor, who was 26 at the time. "We were getting attention."

He said no one at Audi or his promotion firm told any of the drivers or passengers where to go or what to say when people asked questions — but admitted that some did approach them and remark on the cars.

"Nobody had to instruct us," he said. "It’s a good car, anyway. It was a fun job."