The three teens were parked up at the popular spot at 10.30pm when a man approached, asking them if they had drugs.
The victims had arrived in three vehicles, one belonging to one of their mothers, Senior Sergeant Craig Dinnissen, of Dunedin, said.
The offender later tapped on their car window, then smashed it.
They escaped in one of the cars, but when they returned found one of the two remaining, a Ford Kuga, had been stolen.
The Kuga was later recovered in Queens Dr, City Rise.
The offender was wearing a grey hoodie, was of solid build, medium height, and had brown hair.
He had possibly turned up in a champagne coloured Mitsubishi.
Police were keen to hear from anybody who had seen suspicious people in a Ford Kuga in Queens Dr, near Cosy Dell.
