A huge round saucer silently gliding 5,000-6,000 feet above me

I was driving in my car with a friend in the middle of town.  As I came to a stop light, a saucer-shaped disk came into my view overhead.  It must have been on the same path as I was (a main road), and when I came to a stop, it kept going.
The saucer was (rough guess) half a football field round in diameter.  Possibly more.  A huge disk silently gliding through the air!  Set in from the outer diameter a few yards were a ring of lights, pulsating different colors at different timing.  It's been quite a few years past but I recall seeing red and green and possibly yellow lights.  It was riding low in the sky, roughly 5,000-6,000 feet above me.
I continued down the road and the saucer seemed to be going at my pace, staying just over me.  I turned left and the saucer was still over me.  I took one last turn, which essentially  meant I was facing the direction from which I had just come and the saucer is still over me.  I came to a stop and it kept on going soon out of my sight, in the direction from which it came.  At one point I actually thought I was going to be the next abductee!
Date of the event may be approximate, although the witness does not indicate that fact.  PD