@a63nt-5m1th said in Replacing cars but having random crashes:
@DugiHowser
Sounds good

Yeah, not all add-ons like being replaces & vice versa.
Just in case you don't know, you can spawn add-on cars ambiently on the streets (just like a replace would) without having to convert them to a full replace version. Only real downside might be the add-on cars won't appear in scripted storymode events (without a vanilla name) & an add-on dlc uses up available add-on slots (you can combine a heap of add-on vehicles into one add-on dlc to combat that tho).
It's easier & more reliable than converting an add-on to a replace & it's also great from a diagnostic point of view, being able to disable all your personal add-on cars with one edit of 'dlclist.xml' etc 
It all depends on your reason for using replace vehicles of course, they have their place certainly, but for the most part, you can pretty much use an add-on in the same way as a replace, so don't be locked in on having to convert them all to replace to get the functionality you want. There are usually multiple routes to the same outcome as far as replace & add-on vehicles are concerned 
Replacing a vanilla vehicle with an add-on is as simple as editing 'popgroups.ymt'
...\mods\update\update.rpf\x64\levels\gta5\popgroups.ymt
Open 'popgroups.ymt' & find the name/s of the vanilla vehicle you want to replace, & change all of it's name entries (same car often has multiple entries) to the name of your add-on vehicle.
Your add-on will then spawn on the streets in place of the vanilla vehicle.
As mentioned, if a storymode scripted event calls the vanilla vehicle, it will be the vanilla vehicle that is spawned, not your add-on, so you'll want to have at least some full replace versions installed for those cars, but apart from that, replace & add-on vehicle functionality is pretty much identical. 
This is great info I did not know that thank you so much! My end goal is to replace or come close to replacing as many vanilla cars as I can. I truly want to have that "real life" experience lol. Ill start playing around with the popgroups.ymt and update with my results. Thanks again 