TANDEM T6 for GTA IV
Version 1.0.0 (2026-10-18), build 896ca70, plugin 8b05c500
==============================================================================

A tiny tandem two-seat electric car add-on for Grand Theft Auto IV: The
Complete Edition (PC).

A one-metre-wide electric tandem two-seater, built from scratch for GTA IV.
The driver sits in front and one passenger sits right behind, and everyone
climbs in through the front doors. A heavy battery in the floor keeps it
planted: it shrugs off hard corners and kerbs without rolling over, but it
still spins and drifts like a GTA car. It is an add-on car, so no stock
vehicle is replaced.

FEATURES
========

- Add-on car tandemt6: spawn it with any trainer that spawns cars by model
  name. No stock car is replaced.
- Tandem seating: driver in front, one passenger directly behind. Both get in
  through the front doors, and the rear passenger can climb in even when the
  driver is already sitting there.
- Ride in the back: hold the Enter vehicle button next to a Tandem T6 driven
  by a friend or a companion.
- Battery-weight stability: the heavy floor battery keeps it upright through
  hard corners and kerb strikes. It only lets go in really big crashes, and it
  rights itself if it ends up on its side. Spins and donuts still work.
- Live stats on screen: power in kW, speed in mph and km/h, motor rpm, body
  roll and cornering g. Automatic 0-60 mph, 0-100 km/h and quarter-mile timers
  start by themselves from a standstill, and your session's best times show on
  a card when you get in.
- 20 original sounds: motor whine and growl that follow speed and throttle, a
  launch bite with a tyre chirp, carbon doors, the front seat sliding for the
  rear passenger, wind, body rattle, impacts and more.
- Body damage and deformation, like the stock cars.
- No battery to recharge: drive as far as you like.
- Every setting in one file (plugins/TandemT6.ini), and you can change
  settings while you play.

REQUIREMENTS
============

- Grand Theft Auto IV: The Complete Edition for PC, version 1.2.0.59 (Steam or
  Rockstar Games Launcher) on Windows, or on a Mac with CrossOver
- FusionFix (https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix/releases)
  5.1.1 or newer by ThirteenAG and team: it loads the plugins folder (it
  includes the ASI loader) and the update folder where the car lives
- Aru's C++ ScriptHook 0.5.1 (ScriptHook.dll) plus the Complete Edition hook
  fix (aCompleteEditionHook.asi): Hook fixes for Complete Edition
  (https://www.lcpdfr.com/downloads/gta4mods/g17media/26726-hook-fixes-for-complete-edition/).
  The car's plugin runs as a ScriptHook script
- Optional: a trainer that spawns add-on cars by model name, for example
  Liberty's Legacy (https://www.nexusmods.com/gta4/mods/100) 2.4.1

None of these are included. Get them from their authors' pages.

DOWNLOAD AND INSTALL
====================

Installing takes about ten minutes. You copy two folders into the game and
paste three lines into three text files. There is no installer, and nothing in
the game's own common folder is changed.

Before you start
----------------

1. Back up your GTA IV folder (or at least update/ and plugins/).
2. Install everything in the README's requirements: FusionFix, ScriptHook and
   the Complete Edition hook fix. Start the game once to check that they work,
   then close it.
3. Find your GTA IV folder: it is the one with GTAIV.exe in it. On Steam it is
   usually Steam\steamapps\common\Grand Theft Auto IV\GTAIV.

What's in the zip
-----------------

    TandemT6-<version>/
      Game Folder/
        plugins/
          TandemT6.asi          the car's plugin (seating, stability, stats, sounds)
          TandemT6.ini          its settings
          TandemT6/sfx/         20 sound files
        update/
          z-TandemT6/tandemt6.img       the car (model and textures)
          common/text/<language>7.gxt   the car's name and on-screen hints (7 languages)
      Data Lines/
        vehicles.ide.txt        one line for the game's vehicle list
        carcols.dat.txt         one line for the car's paint colours
        handling.dat.txt        one line for the car's handling
      README.txt  LICENSE.txt  CHANGELOG.txt  SHA256SUMS.txt  manifest.json

Install
-------

1. Download TandemT6-<version>.zip from the download section and unzip it. If
   you want to check the download, compare the files with SHA256SUMS.txt.
2. Open the zip's Game Folder and copy its two folders, plugins and update,
   into your GTA IV folder. Merge them with the folders that are already
   there. You don't need to replace any existing file.
3. Add the three data lines. In your GTA IV folder, open update\common\data:
   - If vehicles.ide, carcols.dat or handling.dat is missing there, copy it in
     from common\data first. Never edit the files in common\data itself.
   - If another add-on car already put these files there, keep them and add
     our lines to them.
   - Open each file in a plain text editor (Notepad works) and paste the line
     from the matching .txt file in Data Lines. Each .txt file says where its
     line goes:
   - vehicles.ide: inside the cars section, just before that section's end
     line
   - carcols.dat: inside the car3 section, just before that section's end line
   - handling.dat: on its own line among the other car rows
   - Paste the lines exactly as they are (they contain tabs) and save as plain
     text.
4. Start the game and spawn tandemt6 with your trainer. With Liberty's Legacy,
   add tandemt6 on its own line to the trainer's add-on car list (Liberty's
   Legacy\Lists\addon_vehicle_models.txt in your GTA IV folder), and the car
   shows up in its add-on vehicles menu.
5. Get in. A short hint shows the controls, and the stats card shows your best
   times (controls).

On a Mac with CrossOver
-----------------------

Do the same steps inside your CrossOver bottle:

1. In CrossOver, open the bottle's C: drive and go to the GTA IV folder,
   usually Program Files (x86)\Steam\steamapps\common\Grand Theft Auto
   IV\GTAIV.
2. Follow steps 1 to 5 above in that folder.
3. If no ASI mod loads at all, set a DLL override in the bottle's Wine
   configuration: dinput8 = native, builtin. FusionFix's own readme explains
   this.

Uninstall
---------

1. Delete these from your GTA IV folder:
   - plugins\TandemT6.asi, plugins\TandemT6.ini and the folder
     plugins\TandemT6\
   - the folder update\z-TandemT6\
   - the seven text files update\common\text\american7.gxt, french7.gxt,
     german7.gxt, italian7.gxt, japanese7.gxt, russian7.gxt and spanish7.gxt
2. Remove the three Tandem T6 lines from vehicles.ide, carcols.dat and
   handling.dat in update\common\data. If you copied those files there only
   for this mod and no other mod uses them, you can delete them instead.
3. If you added tandemt6 to your trainer's add-on list, remove that line too.
4. Before you uninstall, don't leave the car in a safehouse garage. Get out of
   it somewhere else, then save.

Troubleshooting
---------------

- The trainer can't spawn tandemt6, or the game says the model isn't found:
  Fix: Check that update\z-TandemT6\tandemt6.img is in place and that the
  vehicles.ide line is inside the cars section of
  update\common\data\vehicles.ide.
- The game crashes while loading after you added the lines: Fix: A data line
  is broken or in the wrong section. Paste it again from Data Lines, with its
  tabs. Make sure the TANDEMT6 row is in handling.dat, because the
  vehicles.ide line refers to it.
- The car's name shows as TANDEMT6 or nothing at all: Fix: The text files
  update\common\text\*7.gxt are missing, or another mod replaced them (see
  Known issues in the README).
- No stats, no hint, no rear-seat boarding, no custom sounds: Fix: The plugin
  didn't load. Check that ScriptHook (ScriptHook.dll) and
  aCompleteEditionHook.asi are installed. plugins\TandemT6.log says what
  loaded.
- No motor sound: Fix: Check that the 20 files are in plugins\TandemT6\sfx\,
  that [Sound] Enabled=1 in plugins\TandemT6.ini, and that the game's SFX
  volume isn't at zero.
- The horn is silent: Fix: That's expected: see Known issues in the README.
- K or the controller chord does nothing: Fix: The game window must have
  focus, and the keys are ignored while a trainer menu is open. Check [Keys]
  and [Pad] in plugins\TandemT6.ini if you remapped them.
- The stats overlap another HUD mod: Fix: Move them with [Hud] X, Y, CardX and
  CardY in plugins\TandemT6.ini.
- On a Mac, no mod loads at all: Fix: Set the dinput8 DLL override (see "On a
  Mac with CrossOver" above).

When you report a problem, attach plugins\TandemT6.log and say which game
version and other mods you use (report a bug).

CONTROLS
========

The car drives with the game's normal controls. These are the extras. A short
hint shows them each time you get in.

- Stats: card, live stats, off (cycles): Keyboard: Tap K, Controller (Xbox
  layout): Hold LB, click R3
- Reset the timers and the top speed: Keyboard: Hold K (0.6 s), Controller
  (Xbox layout): Hold LB + R3 (0.6 s)
- Get in as the driver: Keyboard: The game's Enter vehicle key (F by default),
  Controller (Xbox layout): Y
- Ride in the back of a Tandem T6 driven by a friend or a companion: Keyboard:
  Hold Enter vehicle (F) next to it, Controller (Xbox layout): Hold Y next to
  it
- Get out (either seat): Keyboard: The game's exit key (F by default),
  Controller (Xbox layout): Y

How the seats work
------------------

- The driver sits in front and the passenger sits directly behind. Both get in
  through the front doors.
- The rear passenger opens a front door and climbs through to the back, even
  when the driver is already in. They get out the same way.
- Companions (bodyguards, friends) use the rear seat. They walk to a front
  door by themselves.

The stats
---------

- Card (shown for a few seconds when you get in): your best 0-60 mph, 0-100
  km/h and quarter-mile times this session, the quarter-mile trap speed and
  your top speed, all measured in game.
- Live stats: power in kW (and amps), speed in mph and km/h, motor rpm, then
  the timers, then body roll, cornering g and what the stabiliser is doing.
- Timers start by themselves: come to a full stop, wait a moment, then
  accelerate. Hold K (or LB + R3) to clear them.

Notes
-----

- The keys only work while the game window has focus, and they are ignored
  while a trainer menu (such as Liberty's Legacy) is open, so menu buttons
  don't reach the car.
- L3 stays the game's horn: the car never reads it.

Changing the keys
-----------------

Open plugins\TandemT6.ini in a text editor:

- [Keys] Hud=0x4B is the keyboard key as a Windows virtual-key code: 0x4B is
  K. For example, 0x4C is L and 0x4A is J.
- [Pad] ChordA=0x0100 and ChordB=0x0080 are the controller buttons as XInput
  values: 0x0100 is LB and 0x0080 is R3. Others: 0x0200 RB, 0x0040 L3, 0x1000
  A, 0x2000 B.
- [Pad] HoldMs=600 is how long a press counts as a hold, in milliseconds.

To apply a change while the game runs, change [Live] Serial (for example from
0 to 1) and save. The car reloads its settings within a second.

KNOWN ISSUES
============

- No horn, engine or tyre-skid sounds from the game itself. GTA IV gives
  add-on cars no audio entry of their own, and that file can't be shipped with
  a mod. The car's own sounds cover the motor, launch, doors, seat, wind,
  rattles and impacts, but the horn is silent.
- Companions boarding the rear seat is the least tested part. If a bodyguard
  or friend gets stuck at the door, step away a few metres and let them try
  again, and please report it.
- Text slot: the car's name and on-screen hints use the game's <language>7.gxt
  text files. Another mod that uses the same slot will clash with it. Tell us
  and we'll move to another slot.
- On-screen stats sit on the right-hand side of the screen and can overlap
  other HUD mods. Move them with [Hud] X, Y, CardX and CardY in
  plugins/TandemT6.ini.
- The data lines are added by hand: there is no installer (see the install
  steps).
- Developed and tested on a Mac with CrossOver. Windows should behave the
  same, but it hasn't been tested yet.

CREDITS, TERMS AND SUPPORT
==========================

Credits
-------

- Author: perlytiara
- Built with:
  - Blender (https://www.blender.org) 5.2: the car is generated by our own
    Python scripts, not modelled by hand or taken from anywhere
  - Python 3 and numpy: our own converter to GTA IV's model, texture and
    archive formats, the procedural textures and the synthesized sounds
  - MinGW-w64 (GCC) to build the plugin, and clang for its tests
  - The game's own vehicle skeleton template, so the car moves and breaks like
    a stock car. No Rockstar meshes, textures or sounds are included.
- Third-party code and assets: none are included. The model, textures, sounds
  and plugin are all original.
- Needs, and thanks to: FusionFix
  (https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix) by ThirteenAG and the
  FusionFix team, Aru for the C++ ScriptHook, the authors of the Complete
  Edition hook fix, and the GTA IV modding community, whose research on the
  game's file formats and script functions made this possible.

AI use
------

Some mod sites require this disclosure.

Tandem T6 was made with AI coding assistants (Claude by Anthropic and OpenAI
Codex), directed by the creator.

- Written by the AI assistants: the plugin code, the Blender scripts that
  generate the model, the tools that convert it to GTA IV's formats, the code
  that generates the textures and the sounds, and these documents.
- Done by the creator: the idea, the look and the features, every decision
  along the way, and testing the car in game.
- No AI image, video or audio generators were used. The model is generated
  from code, the textures and the 20 sounds are synthesized by code, and the
  pictures on this page are renders of the mod's own model.

Terms of use
------------

LICENSE.txt in this folder: free to play and show, no re-uploads, never sold.

Tandem T6 is an unofficial fan-made mod. It is not affiliated with, endorsed
by or sponsored by Rockstar Games or Take-Two Interactive. Grand Theft Auto
and Grand Theft Auto IV are trademarks of Take-Two Interactive Software.
