I have had Porsches since my 64 356C, bought in 68. It used to be Porsche owners ALWAYS flashed lights back and forth. But those were the days when enthusiasts owned Porsches, not snobs.
I live in Brumos country so Porsche enthusiasts have a history predating even Peter Gregg and Hurley Haywood, going all the way back to Avery Brundage. Brumos Porsche has been a landmark for Jacksonville and sportscar racing for well over 30 years, so I still get quite a few returns of the lights. Some just look at you and the sales force has a running joke about new owners questioning all the other Porsches flashing lights at them. They are good spirited about it and explain it to the newbies, some of whom actually get it. When traveling away from Jax, loss of return flashes seems exponential to distance, other than nearing another racetrack on race weekends.
Light flashing was so important to Peter Gregg he had his first 928 modified by his service department to swivel the headlights into working position, flash and return to normal position! I have no idea what that cost him (beside about 10% of what it would have cost one of his customers!!
) but it took his head mechanic and parts manager several days to work it out to Peter's perfection demand.