You might also benefit from some RF shielding on both the Pi and the cable. The Pi throws off a huge amount of RFI , to the point where even a cable plugged right into it is going to catch some too. Use a grounded case on the Pi (or just put it in an Altoids tin with standoffs) and a grounded plug too. Don't forget to ground the Pi case to the car's ground too.

@PUME04 lol no problem, you may want to google "Retropie CRT edition" I've been using that with a pi 3 and a vga666 into a vga to component transcoder .. yes you will spend a bit more money but it works so well ,, but you can not do 480i ,, but its set up to handle all the wacky arcade resolutions per game all done from a config file.

this is the transcoder .. well hes out of stock but keep an eye on him.. about 50bucks

https://www.ebay.com/usr/linuxbot3000?_trksid=p2047675.l2559

and I use this type of vga666 works really well ..

https://www.ebay.com/itm/1PCS-New-VGA-Shield-V2-0-Expansion-Board-For-Raspberry-Pi-3B-2B-B-A-M-/152351022612