Firstly, make sure you have these tools.
IMGed (or IMG Tool). I recommended IMGed since it is quicker and easier than IMG Tool .
Dmagic's wheel mod (for custom wheels)
After downloading your car, extract the .ZIP or .RAR file. When you have done that, make sure there is a .DFF and a .TXD File. Also please read the readme.
Now if you want the car you downloaded to replace a different car, rename the .DFF and .TXD Files to what you want it to replace. Don't put it's full name though. So if you want it to replace the esperanto, don't rename it to esperanto. Name it to esperant.dff, and do the same with the .TXD. Landstalker is landstal.dff and landstal.txd. Find what it is for the car you want to replace.
Now open the gta3.img file, with IMGed, but make sure it isn't read only. Now find the car you want to replace, delete the .DFF file for it, and add the new one by going to actions> add> then the new .DFF. Make sure it is spelt the same as the car that was deleted. Now unlike IMG Tool, you don't rebuild archive. Just exit when you have replace the .DFF File.
Now just do the same in Txd.img file. Delete the .TXD file off, then go to actions> add, then add the new .TXD. Again make sure that it is named the same as what got deleted.
NOTE: If there is no txd.img, run the game and load or start a new game, then you will get a message saying, "Converting textures." When that's done txd.img is created as well as txd.dir
Now for the handling.cfg. Copy and paste the new handling line from the readme, and paste it over the handling line that you would like to replace.
NOTE: It doesn't matter if there is a number in the handling line that is not in line.
It will not crash the game.
That doesn't matter.
Now for Default.IDE, find the car that you replaced, and change the numbers that it tells you to change. Do not worry about spaces. Just make sure there is a space or more between each number. Change the wheel indentfier to 089 for custom wheels to appear.
NOTE: If you set the cars wheels indentifier to 089 and it has no new wheels, it will have no wheels. You may make the car have any orginal wheels by reading the description at the top.
Now for carcols.dat. Paste the new car colours line over the old, and save than go and test your car! Make sure that you remove the old one's though!
If you replaced a 4 door car with 2 door or 2 with 4, read my guide on replacing collision files. Although it is for Vice City, just do the same with vice city.
I've reliased if you put any car in the garage, than replace it, the game crashes when you try to open the garage up. But the car works fine anywhere else. It doesn't happen all the time.
Using IMG Tool
1. Make sure gta3.img and txd.img file aren't read only.
2. If there is no txd.img, run the game and load or start a new game, then you will get a message saying, "Converting textures." When that's done txd.img is created as well as txd.dir. You will not be adding any new files in there.
3. Now open gta3.img with IMG Tool, go to edit>find, than type the name of the car you would like to replace. Delete it off, then go to commands> add, making sure that it is spelt the same as the car that was deleted.
4. You need to rebuild archive. Go to commands>Rebuild Archive.
5. When it is done, open up txd.img. Now just do the same as what you done in gta3.img, except this time you need to delete the .TXD for the car and add the new one.
6. All done for gta3.img and txd.img
Edited by gtamodder, 05 October 2007 - 06:38 PM.