Realistic 4x4 Traction System

How to test the mod:
1. Choose a rear-wheel-drive (2x4) tractor in Manual mode
2. Accelerate on a hill or soft ground
→ The rear wheels will spin
→ The HUD shows wheel slip

3. Switch to Semi-automatic or Automatic
→ The mod detects actual wheel slip
→ 4WD engages automatically
→ The HUD switches to 4WD
→ Wheel slip stops

4. Test Intelligent mode (Fendt)
→ 4WD engagement increases gradually based on wheel slip
→ It’s not just on/off—it’s progressive
A dream years in the making.

I’m a long-haul truck driver. Farming Simulator has always been my escape between trips—but something had bothered me since the very first version I played: the 4WD system never felt realistic. It was always just an on/off button, if it existed at all. There was no realistic differential behavior, no automatic engagement; nothing like what actually happens in a tractor when the wheels start losing traction.

I never had the time to do anything about it—until now. Over the last few months, I dedicated every spare minute at home between trips to this mod: reverse-engineering the game's physics, learning how to create FS25 mods from scratch, testing, breaking things, and testing again. I used AI assistance throughout the process—to study the game's inner workings, learn scripting, and help write and debug the code—and I want to be transparent about that, as I think it's only fair to mention.

This is the result: a 4WD system based on real differential physics, not just a visual feature.

What it offers:

🔧 Real differential physics—front-axle engagement and differential locking directly affect the vehicle's physics, rather than being merely a visual effect. 🎚️ Four traction modes, assigned to each tractor based on its real-world transmission type:

Manual — you decide when to engage it
Semi-automatic — engages automatically upon detecting actual rear-wheel slip, with a manual control option
Automatic — same principle, for tractors with "classic" automatic systems
Intelligent (Fendt VarioDrive) — gradual, continuous engagement proportional to slip intensity, with no fixed ratio—exactly like the real system

🛞 Real slip detection — not based solely on speed: the mod reads actual wheel slip to decide when 4WD should kick in.

💧 Optional synergy with the variable tire pressure system — if installed, tire pressure automatically adjusts between field and road modes as 4WD is engaged or disengaged.

🖥️ Adjustable in-game HUD — reposition the indicator directly within the game's General Settings menu; no file editing required. 🚜 Limited to tractors, trucks, harvesters, and cars — does not work on trailers, implements, forklifts, or other unsuitable vehicles.

Requirements: Single-player mode only for now (no synchronization on multiplayer servers yet).

Credits: The differential manipulation technique was confirmed via reverse engineering of the FS25_EnhancedVehicle mod; tire pressure integration utilizes the public API of the Variable Tire Pressure mod. No third-party code was copied—only the techniques were studied and reimplemented from scratch.

This is the first public release, created by someone who had wanted to see this feature exist for years and finally found the time to make it happen. Feedback is highly welcome—if something doesn't work correctly on your tractor, please let me know the model, and I will make the necessary adjustments. Changelog

v1.0.0 — Initial release

4x4 drive system based on actual differential manipulation (not just visual)
Functional differential lock per axle
4 configurable drive modes per vehicle: manual, semi-automatic, automatic, and intelligent (Fendt-style)
Automatic engagement based on actual rear-wheel slip detection, featuring hysteresis and confirmation delay
Intelligent mode: gradual, continuous engagement proportional to slip, with automatic deactivation at road speeds
Optional integration with the Variable Tire Pressure mod (automatic field/road adjustment)
On-screen HUD displaying drive state (4x4/2x4), drive mode, and differential lock status
Adjustable HUD position in the game's General Settings menu
Automatically restricted to tractors, trucks, harvesters, and cars
Initial support for major tractor brands (see the DriveModeConfig.lua file for the full list)