Why most modded cars crash in Assetto Corsa on Mac, and how to fix it

If you’re running Assetto Corsa via CrossOver on an Apple Silicon Mac, you’ve probably noticed that many community mods refuse to load. The game crashes immediately when you try to enter a session with certain cars. Factory (Kunos) cars work fine. Some mods work. Others crash every single time, no matter what settings you change.

This guide explains exactly why this happens and how to fix it for most affected cars.

The short version

Many mods are built with CSP Extended Physics — an alternative physics engine that calls Windows APIs that CrossOver (Wine) cannot emulate. When the game tries to load one of these cars, it hits an incompatible API call and crashes before the session ever starts.

The fix is to tell AC to use the standard physics engine for that car instead. For most mods this takes about 30 seconds.

What is CSP Extended Physics?

Custom Shaders Patch (CSP) is the community mod framework for Assetto Corsa on Windows. Among many visual and gameplay improvements, it includes an alternative physics engine that some mod authors use to add more realistic tyre models, improved suspension kinematics, and better aerodynamics simulation.

When a mod car is built with Extended Physics, its car.ini file contains:

VERSION=extended-2

On Windows with CSP installed, this is fine — the CSP extended engine loads and the car behaves as intended. On macOS under CrossOver, this line causes an immediate crash.

Why it crashes on Mac

CrossOver runs Assetto Corsa through Wine — a compatibility layer that translates Windows API calls to macOS equivalents. It works remarkably well for AC’s core engine. But the CSP Extended Physics engine calls specific Windows system functions that Wine cannot handle.

The crash shows up in logs/log.txt like this:

unhandled exception code c0000005 at 00006FFFFFC1CF77

The memory address 00006FFFFFC1CF77 is in the upper half of the 64-bit address space — a signature of a Wine-incompatible Windows kernel call. There’s no workaround at the CrossOver level; the call simply doesn’t exist in Wine’s implementation.

Why the global CSP setting doesn’t help

You may have tried setting EXTENDED_PHYSICS=0 in your CSP configuration, or disabling extended physics globally in Content Manager. This doesn’t fix crash-prone cars.

That global setting means “don’t force extended physics on all cars.” It does not override cars that explicitly request it via VERSION=extended-2 in their own car.ini. Those cars will always attempt to load the extended engine, regardless of the global flag.

How to identify affected cars

Not all mods use Extended Physics — only those explicitly built for it. A reliable way to find which ones are affected:

1. Open a terminal
2. Run:

grep -r "VERSION=extended-2" \
  ~/Library/Application\ Support/CrossOver/Bottles/*/drive_c/*/assettocorsa/content/cars/*/data/car.ini

Any car that appears in the results will crash. Cars not listed are unaffected.

The fix

Method 1: Edit car.ini (works for most mods)

This is the simplest fix and works for any mod with an accessible data/ folder.

1. Navigate to the car’s folder inside your AC installation:
   assettocorsa/content/cars/<car_folder>/data/
2. Open car.ini in any text editor
3. Find the line:

   VERSION=extended-2

4. Change it to:

   VERSION=2

5. Save and close

That’s it. Restart AC and the car will load normally using the standard physics engine.

Note: Some mods ship their data/ folder as an encrypted data.acd archive instead of loose files. If you don’t see individual files in the data/ folder (just data.acd), use Method 2 below.

Method 2: Swap to the standard physics package (for mods that ship both)

Professional mod studios often include both a CSP and a standard version of their physics data, anticipating that not all users will have CSP. Look for a folder structure like this inside the car folder:

car_folder/
├── data.acd              ← active physics file
├── physics/
│   ├── csp/
│   │   └── data.acd      ← CSP extended physics version
│   └── standard/
│       └── data.acd      ← standard physics version

If you see this structure, the fix is easy:

# Back up the CSP version first
cp data.acd data.acd.csp-backup

# Activate the standard version
cp physics/standard/data.acd data.acd

Restart AC — the car now loads with the standard physics data.

What you actually lose

Almost nothing for everyday driving.

CSP Extended Physics adds enhancements that are subtle to noticeable depending on the car and how closely the mod was tuned specifically for the extended engine:

• More detailed tyre temperature and deformation modelling
• Improved suspension kinematics under load (toe/camber changes)
• More refined aero simulation (ground effect, downforce stall)

For road cars, GTs, and most touring cars, the difference in feel is minimal. The standard AC physics engine is already excellent, and most mods that ship a standard version take care to make it drive well.

For highly specialised open-wheel mods tuned exclusively for CSP physics, the handling character may differ more noticeably — but the car will still be drivable and correctly modelled at a physics level.

Why Kunos (factory) cars are unaffected

Factory Assetto Corsa cars use VERSION=1 or VERSION=2 in their car.ini. They never request the extended physics engine. The global CSP extended physics setting has zero effect on them — which is why you can enable it globally without breaking any base game content, and why everything works fine until you install a mod that explicitly opts in.

Summary

Most affected mods can be fixed in under a minute. Once patched, they run reliably on Mac with full Torqer force feedback support.