Seen but not photographed: BMW sedan

This one shot by on a short mountain road while I was walking a queasy dog that just saw the vet.  The car was black.  It was either a 5 or 3 series.  It was unlabeled.  It's hard to tell which car is which by the size, because all car companies bloat their cars to no end.  In any case, this one looked ok, and it had a chrome strip above the license plate.  It drove well going down the mountain.  It was fast, and it didn't make any noises betraying any strain.