Just finished watching another great video from the SAFootbaall Archive, the 1974 State match. I noticed that a more conventional lower pitch siren was used. But I know the next season had the car siren. This was used up until 1991, when the current siren replaced it. An extra tone was added to it in 2003, I think I recall some problems with the volume, so another tone was added to it to be heard better.
The car siren has to be the most distinct siren used at a major football venue. I wouldn't mind knowing who came up with the siren; why the 1974 one wasn't kept; and was it an AFL directive to replace it. Seeing as it lasted one season into the Crows foray into the AFL.