My girlfriend asked, "what's that?" and i replied, "a helicopter," as we'd heard a helicopter in the vicinity a little earlier, but then we realized there was no sound. the object was hovering with red/blue/green lights flashing and a white light that looked like a spotlight. it changed positions, and seemed to 'aim' at us from a stationary position, then looked as though it flipped upside while at the same time turning around in a complete circle and then began to drift effortlessly forward. "oh, that's a drone," i said, even though it was much bigger than any i'd ever seen. "maybe a police drone," i added, and everyone agreed. we began to drive forward and the object was going the same direction, so i joked, "let's follow it." once we started following it, it moved quickly forward about a block and a half and then was just gone. we don't know if it changed directions abruptly, or if it landed suddenly, or if it vanished. five of us looking from five different vantage points (including the sunroof) and none of us could see what had happened. i'm still going with the police drone being the likeliest explanation, but felt i should report this, just in case.