GTA Underground 3.3.11.2 / Modded SA - AP Conversion (using teleport to marker)
You can use this method for semi-vanilla game, if you aren't bothered with installing CLEO and this mod: https://www.gtagarage.com/mods/show.php?id=7483
But, for vanilla only players - you better off watching other videos on the same topic.
Basically, if you go on the date and "have a coffee" - you car becomes all-proof for any damage. Not only with this method you gain + to your relationship, but also it's the easiest one.
Why am I still on the 3.3.11.2 version? Well, I'm crash alot in 4.1.6 if I load the savefile, but other than that - that version is more stable excluding save shenanigans. If it wasn't the issue - I would be a happier person. Also 4.1.6 version doesn't come with "Teleport to Marker" mod, so you need to install it separately.
Also, that Patriot is from courier mission - it's FP/EP/BP/MP.
I think I'm gonna drown it or something, since this method makes any car better :P