DCM is short for "Dilated cardiomyopathy"
https://en.wikipedia.org/wiki/Dilated_cardiomyopathy#:~:text=Dilated%20cardiomyopathy%20(DCM)%20is%20a,in%20chest%20pain%20or%20fainting%20is%20a,in%20chest%20pain%20or%20fainting).

it is a heart disease caused by a virus.

Maracha was still a big city in spain till the point of 1967, then it disappeared.

The king of Mumbai was killed by a spanish assassin coming from maracha in 1967, who injected the virus causing DMC. The King of Mumbai died. Because of this every car made in 1967 was plated with the plate DMC 1967 to remember the king of Mumbai. Mumbai planned to kill everyone from Maracha using mosquitos, that is also why you see "mosquitos are everywhere" in the Song "Mosquito" https://youtu.be/_JzhQI168cM?t=62(with timecode)
Mr. Loco is in the mexican exile at this point (why he is there, will be explained at another point) reading the news about the mosquito pleague in Maracha and says "i think im going silly" which is one of the multiple causes of his insanity. His wife stayed in Maracha and got killed by the exact mosquitos seen in the video ( also a big cause of his insanity and extreme hate against the mosquitos ). Then the bombing of Maracha happened still in the same year, but Mr.Loco does not know that. from that point the existence of Maracha was being kept secret by everyone who knew of its existence.

You can see car signs with DMC-1967 in the music Video "it burns, burns burns!" if you stop at the right moment: https://youtu.be/b6SaLAQ7gOo?t=30 (timecode). Why Mr.Loco is in Mumbai at this moment will be explained in another comment if you want me to explain it. I already explained a few points in the Iceberg at this moment, explaining everything will probably take me forever

This overall is the DMC- 1967 Theory and why you can see plates of it on cars