Handling & Physics in GTA 2 Coding

Cars are just 2D images in GTA2. Driving them is more like moving something in an image editor!

During the past decade I have tried several times to understand GTA2 physics. A few things do work reliably and this page is about them. The rest is a mystery!

Different Cars will Always be Different

Even if you use exact same settings in nyc.gci for two cars, they will have different handling. The acceleration and damage might be the same but that’s it.

This might be due to the the axle positions in the *.sty file. Would need more testing to confirm this.

Viewing the Handling File

Your gta2\data folder has a file called nyc.gci which contains the handling for every car in every level. Make a backup of this before you start changing any values!

You can open the file with Notepad. Read the instructions at the bottom of my Tools & Editors for GTA 2 list. You can also use the GTA2 Power Manager. t adds a Physics tab which lists all the cars. Selecting a car loads all its handling values into boxes with sliders.

To get a good overview and compare the data, you have to see lots of cars at the same time with the data nicely aligned. So I turned the data into a spreadsheet, which you can download here:

Download nyc.gci Spreadsheet (CSV, 13kB): Opens with any spreedsheet program (like Microsoft Excel) or text editor (like Notepad). Includes the original handling, so you can restore your changes easily.

Acceleration

Each gear has an acceleration curve. They start by accelerating very fast but this reduces a lot as the speed increases. You can only reach top speed in 3^rd gear if the curves overlap. The Dementia sometimes won’t reach 3^rd gear because the overlap is very small.

Relevant Settings

Several values affect acceleration and top speed:

Thrust: The power of the engine.
Turbo: Increases power when at higher engine speeds (rpm).
Gear n Multiplier: This value increases power and speed at the same time. Not like the gear ratios in a real car!
Rear Stability: Yes, this actually has a big effect. Bigger values make the car slower. Did I mention GTA2 physics are weird?

The max_speed value sets a limit on the top speed. The car can only reach this speed if the other settings are correct. A car cannot go faster than the max_speed value.

Realistic Performance

You should make 1^st gear quite powerful but never as powerful as 3^rd. 2^nd gear can be quite close to 1^st. Make sure 2^nd lets you go fast enough to reach 3^rd!

It is quite nice to set 3^rd gear so you only just reach top speed. Then the car will accelerate gradually when you are at high speed. You must carry speed through the corners and a take good racing line to reach the highest speed, a bit like real racing.