Here is the definitive guide to installing a vehicle into Vice City.
A few things to remember:
1) ALWAYS BACKUP FIRST
2) You are replacing an existing car, not adding a new one. So choose which car you want to get rid of. Bear in mind that your car will appear wherever the car you replace appears.
3) If your mod is set up to replace one particular car (eg the files are called infernus.txd etc) then you can change it to replace a different mod. The VCMM will allow you to do this when you install, but if you do it manually you will have to rename the .txd and .dff to the exact filename you want to replace (eg blistac) and then when you edit the handling.cfg files etc, change the name and/or ID of the car. This is a dangerous process
4) Sirens (flashing blue lights on emergency vehicles) cannot be switched from car to car, so you can't have more than already exist (police car, ambulance, fire truck, fbi washington, fbi rancher). Replacing these cars will give you a siren.
5) Car's files have the cars internal name in them. Inside all the configuration files and the archives, the Blista Compact is called 'blistac', the Police squad car is called 'police', the FBI washington is called 'fbicar' and so on. Most of the names are understandable. DO NOT rename any of these files to more befitting names, the game will look for the 'blistac' car not the 'dodge' car. This will only muck up your game. If you want to rename a car so it shows a different name ingame, i'll show you how to do that later on.
6) Vice City mods will NOT work with San Andreas. SA mods are made differently, and often require different installation techniques.
7) Only the PC version of Vice City is moddable, it is too long and expensive a process to attempt to install a mod on the XBox or PS2 versions. It basically involves you replacing the files on the disk with the new ones, and burning them to a new disk, then modifying your PS2 to be able to play recordable disks. For the same amount of time, money and effort you could upgrade your PC and buy the PC version and mod that easily. Just get the PC version.
8) ALWAYS BACKUP FIRST
The Vice City Mod Manager (vcmm) is an application that can help you to install specially prepared mods into Vice City. Its basically a lot of extra work by the modder to make it easier for you to install.
To install a VCM mod you firstly need to download and install the Vice City Mod manager (from thegtaplace's downloads section), and you need to download the VCM version of the mod/vehicle you wish to install - the normal dff/txd version will not work. Follow the steps below to install a vcm mod.
Place the .vcm file in the [C:\Program Files\vcmm\mods\vcm] folder
Run the Vice City Mod Manager
Select the mod you wish to install (it will automatically detect it)
Choose the car you wish to replace with your mod
It will replace the shape, size, colours, handling and name of the vehicle
Before you install any VCM vehicle mods you MUST install "DMagic1's wheel mod". Without this installed, your game will crash after you've installed the mod. When you download DM1's mod, you follow the above process, the same as you would to install a vehicle, except you dont choose a vehicle to replace.
If it comes up with an error when you try to install it, notably ones that say 'IMG' or 'dir' on them, there is an extra thing you have to do before you can install it. Note this is for Microsoft Windows:
1) Browse into your Vice City directory [C:\Program Files\Rockstar Games\Grand Theft Auto Vice City] then go into the \models\ folder.
2) Right click on gta3.img and click properties
3) Untick 'read only' if it is ticked, and click ok
4) Right click on gta3.dir and click properties
5) Untick 'read only' if it is ticked, and click ok
To install a mod manually takes a bit more effort, and a few more things can go wrong. Most mods are available in this format. Please note it is NOT just a case of putting the DFF and TXD file into the Vice City folder, you need to put the files into a special archive.
You need to download IMG Tool to install all vehicle mods, and download the normal version of the mod. VCM installations won't work like this.
1) As described above in the VCM section, you need to make sure gta3.img and gta3.dir are not read-only, or you wont be able to do anything to them
2) if you can, copy gta3.img and gta3.dir into a backup folder, just in case you make a mistake
3) With IMG tool, open up gta3.img in the \models\ folder in your Vice City directory.
4) Find the DFF and TXD files in the IMG tool with the same names that you see in the mod you downloaded. Do not look for any COL files or any other files, DFF and TXD only - there will be one of each with the cars internal name (eg blistac, admiral, police, fbicar)
5) Make a backup of those files. Export them to a backup folder somewhere.
6) Replace the selected files in the IMG with the ones in the mod you downloaded (if replace doesnt work, delete them and import the new ones) Be warned that you cannot replace them if you delete the wrong ones, so make a backup first.
Editing the associated handling.cfg, carcols.cfg and default.dat files will be explained later.
Collision File Editing
If you find that when you install a mod, it only changes what the car looks like, but its still left with the invisible shape, size and shadow of the old car, it means that you have replaced a big car with a small car, or vice versa, and not changed the collision file for it. This can happen, for example, if you replace the coach with a small car through manual installation. This will give you what looks like a small car, but it will be slow and sluggish and appear to bash into things that are quite a distance away from it. This can also happen if the author put the wrong collision file into the .vcm file.
The best thing to do is to look for a replacement collision file, either by looking on the modder's website for the latest version, or checking if theres one in the download. If you find a replacement mod, install it. If you find a replacement collision file, follow the steps below but replace the collision for the car with the one you downloaded, instead of extracting a similar one from a similar car:
Download, install and run colmanager (collison manager) downloadable from codenameGTA HERE
With that, open up the vehicles.col file in your vice city directory in \models\coll\ - but make sure the vehicles.col file is not read only first (right click on it, properties, untick it, ok)
If you click on the vehicle you replaced with the downloaded car (eg blistac) you will see the big coach. Thats the physical layout of the vehicle you're driving. You ideally want one that fits it better, so have a look at the others and choose one thats a similar size/shape. For example it may look a similar size to the Admiral, and the pony might be too big.
Export the chosen model, (eg admiral) to your desktop. Then go to the original one with the coach model (eg blistac) and replace that model with the one you exported to your desktop. Either replace or delete it then import the new one and rename it to the model name (eg blistac).
That will replace the bad model with the model that should fit your car better. Try it out, and if it doesnt quite fit, you could always try to do it with another replacement model. Just don't get confused about the model named 'coach', that is the model for the 'coach' vehicle. Also don't rename it to something like 'bmw', that isn't how it works - the game looks for the model called blistac to put where the Blista Compact car is. These collision files are not the visible model, but the physical model, so it won't affect the look of the car, just the invisible shape and its shadow.