A New Jersey motorist rigged his E-ZPass reader to a mooing cow toy and made a video showing how cars with the devices are tracked through New York City, far beyond toll plazas.
The man drove from Times Square to Madison Square Garden, a short distance, and the cow mooed five times, according to the video.
The driver, who wanted to remain anonymous, told NBC 4 New York he set up the experiment because of privacy concerns.
"People sign up for E-ZPasses to pay the toll," he said. "I don't think a reasonable person expects to be tracked at that level."
The transceivers are not difficult to distinguish: they're rectangular metal boxes hanging from traffic light poles.
The city Department of Transportation says E-ZPasses have been tracked throughout Manhattan, Brooklyn and Staten Island for years. The information is used for traffic management, and the readers collect only aggregate information, which is scrambled and does not identify individual motorists, officials say.
That's reassuring to some drivers but not to others.
"It's a little intrusive," said one man.
But another said, "To get through the toll booth so quick with that, it's well worth it."
Drivers can opt out of being tracked by placing their E-ZPasses in the foil bags they come with.