Here's how to replace as many cars as you want without crashing!
First, let's get this out of the way: installing many car mods will make your fps drop. It's logical because you're loading many times more data than with the vanilla vehicles, so if you want to replace many cars, I suggest you have a nice PC. My rig can handle as many mods as the game can take but I can feel the drops here and there (FX-8350 @ 4,4GHz; 8GB DDR3; R9-280X 3GB w/ hard OC). Also never forget: ALWAYS make backups! Starting from scratch because you forgot to back up your game and don't know what you did wrong can induce great rage. When you have mods and your game doesn't crash in 30-40 minutes of intense gameplay, you make a backup.
Anyways, the important stuff start from here.
So I've been replacing cars for a few days now, and I have finally understood how the game works. I'll share it with you so you don't have to learn the hard way (which is making your game crash and losing your shit).
So what the game does is it loads a specific amount of vehicles in a temporary pool and these cars appear in traffic at that time. All vehicles you see on the road are in this pool.
Now look at the size of the default GTA V vehicles, the .yft and .ytd files. Less than 3-4MB in most cases! Now look at the mods you download. They're almost all bigger than that, those that aren't are very bad quality and are not even worth replacing in most cases. A good quality car mod will be about 10MB in size or even more - some exceed 30-40MB even!
Now the game's engine is not designed to load this much data into this temporary pool for cars. When you start replacing cars, you'll notice the variety of traffic is already decreased - that's a consequence of the bigger sized models as well (and there's a mod that fixes it: https://www.gta5-mods.com/misc/non-redundant-popcyle-for-modded-vehicles).
When you download cars bigger than around 20-25mb in total size, that's when the game crashes. It might not crash when you only have a few of these and no other replaced cars, but when the game picks two or more of these huge cars to load in traffic at the same time, it won't be able to do that. Imagine when it tries to spawn two of your 35MB vehicles - it's about 20 original vehicles in size!
So all you have to do to avoid memory errors and random crashes is to keep your car mods under 25 (or if you have a lot of cars replaced, make it 20) megabytes each. This of course means you won't be able to install some nice mods (the ultra-detailed ones), but you gotta make compromises, and trust me, mods around 15-20mb can already be more than good enough. I have about 90 cars replaced now as well as 30 add-ons added to the traffic, my game runs as well as vanilla. Here's two modders whose mods are usually nice, immersive (I always use them) and well-sized:
Of course there are mods that will make your game crash anyway because they are simply bad conversions, but you can definitely tell that from the comments sections of mods.
Also, here is another mod I strongly recommend to avoid crashing by incompatible modifications on replaced cars:
So, again, here's what you should look out for:
-Don't install mods with a larger total file size than 20-25mb (.ytd and .yft files together).
-Always check the comment section, especially for mods with low rating or not many downloads
-Stress test your game! It is time consuming and can be boring at times, but play for about 20-40 minutes, and do some heavy stuff. Drive fast, fly low above the city, blow things up, y'know, just your ordinary GTA gameplay, make the game load a lot of stuff. I often just pick a waypoint at the other side of the map, get a driver in my car and let the game run on its own, that works as well. This way you'll be sure your game works fine. If it does, then you MAKE A BACKUP BEFORE CHANGING ANYTHING!
-If your game crashes with a memory error or just "stops working", before killing the first person in your close vicinity, look for the biggest car mod you have installed and replace it with something WAY smaller! You can sort files in OpenIV by size.
Also according to @Willief23's comment under the post about the vehicles.meta frequency setting: if you have a vehicle with a bigger file size and you really don't want to get rid of it, and/or it happens to be something rare (like a LaFerrari or Lamborghini Miura, etc.), setting the frequency value and maxNum value lower in vehicles.meta for that specific vehicle helps not only to lower the memory load, but also to add some realism (you don't see 10-15 LaFerraris at the same time around the corner do you). The frequency value defines how often the car is chosen by the game to spawn (it's a percentage value: 0-100, I recommend 10 for rare cars), maxNum value sets how many of the car will the game spawn at the same time (I recommend setting it to 1 or 2 for rare cars... even 3 LaFerraris queuing up seem a little weird for me).
Hope this little guide will prevent broken keyboards and displays all around the world.
I'd also like you to know: replacing almost all cars in the game is days or weeks of work: researching which is the best replacement for each car, finding one that fulfills the criteria mentioned above, and then testing the game - and making it crash at one point. With this method, that point will come later, but it will probably happen, and then you'll have to repair it by either restoring your previous backup, or just trying to figure out what causes the issue (most likely your biggest car mods). Odds are you'll be bored of the game before you're finished, happened to me, but then I made a backup of the work done and when I felt like playing the next time, I already had a nicely modded game to start with.
If you want to see how to make your add-on cars spawn in traffic (the same rules apply to them!), here's my tutorial video on that topic (how to install add-ons is also on my channel):
@ModHunter and to take it a step further you can go under vehicles.meta file of the addon car or search for vehicles.meta with openiv and find the model car you replaced and then search for frequency this is the spawn frequency percentage and then the amount of that car is 1 line below it. the number value isnt really accurate if i set it to 9 it will still spawn around 10-13 cars around town or in a certain area. Eventually when you replace too many cars with addon cars you will run into roads and buildings flickering on and off or disappearing all together. Gameconfig edits will help some but only for a bit. Older game versions are better for less graphical glitches. 1.0678 up to 1.0877 are really the only newer game versions you want to play on. The older game version you play on the less chance you have of graphic issues and can add more cars etc.
@Willief23 I didn't even know about the frequency setting! I guess if you change that to a lower number for your bigger cars it may help.
For the record, I barely have any flickering although I don't see a single original car in my game anymore around Los Santos and I use the newest version of the game. Only thing that happens rarely is when I suddenly look behind when driving fast buildings seem to appear. But it's a rare thing.
bro! You are my hero! I was seaching the whole internet about this info as I do like to have a lot of modded cars in my game.
@Bubu886 Glad I could help!
Good tutorial, I learned a few things here. I do have advice on replacing cars faster.
I replace 120 or so cars in game in seconds with the EMF mod. Once you build a folder of cars (you place all loose car files in a single folder) you can add it to your game when you need to re-mod in seconds. I replace all weapons, most cars, and some peds in like 2 min. I can start from scratch and mod the game with all new cars (including tuning parts), new rims, new weapons, new weapon sounds, Visual V and Natrualvision, RDE, about 4-5 other scripts (only well optimized scripts) in less than 1 hour. I prefer to replace cars as I have taken the time over the past year or so selecting only the best cars with a good quality to file size ratio. If the car spawns in traffic I keep it under 15 MB.
I have an i7 and a 980Ti and I get a stable 50 FPS in 2560x1440 all day. The most time consuming thing is building your vehicle folder, but take your time and do it right, once it's built you never have to replace cars one at a time ever again.
So for those that want to check it out, EMF folder can be found here: https://www.gta5-mods.com/tools/car-weapon-folder-for-replacer
I've noticed most replacer\add-on cars have huge texture archives. Many textures inside are unused, or there are complete transparencies @ 4k sizes for nothing. I just go in and delete the unused ones, or downsize the (example 4096 red caliper texture) ones that have zero reason to be so high. If the user is savvy they can do this also.