Instructions
Go to an online site that offers free modifications (mods) for "GTA IV."
Click on the link that says "Downloads."
Click on the link that says "GTA IV."
Click on the "Mods" link.
Type the word "Installer" in the search box and click "Find" or "Search."
Click on the appropriate modified file installer for "GTA IV."
Click on the "Download" button. Click "Save."
Open the downloaded file and double click on "GTA Mod Installer." Click on "Extract all" when prompted about the "Compressed (zipped) Folders." Select the destination for the folder and click the "Extract" button.
Double click the "GTA Mod Installer application.
Click "Yes" when prompted "Do you want to allow the following program from an unknown publisher to make changes to this computer?"
Click "OK" when the mod installer has been installed.
Go back to the download site. Click on the link that says "GTA IV" again.
Click on "Cars / vehicles."
Type the word "Formula" in the search box and click "Find" or "Search."
Click on "Ferrari F1 (Formula One).
Click on the "Download" button. Click "Save."
Go to the "GTA: IV" folder on your computer and run the file "LainchGTAIV.exe" in admin mode (a prompt will ask you how you want to launch the application).
During the game, launch the "Main Menu" and click "Car Spawning."
Scroll to "Spawn Ferrari" and click.