Docs/Physics

Vehicles

Create drivable vehicles with wheel colliders and realistic physics.

24 min read Intermediate Updated 2026-07-01 v2.0 ~83 min to complete

Introduction

Vehicle physics is one of the most complex physics systems. This guide covers wheel colliders, steering, engine force, suspension, and anti-roll stabilization.

Guide 13 of 25

This is part of the Intermediate Guides collection. Category: Physics. Estimated completion: 83 minutes. Difficulty: Intermediate.

Screenshot

Step-by-Step Guide

Create the car body

Add a box rigidbody for the chassis. Set mass (800-1500 kg) and a box collider.

Add wheel colliders

Attach 4 Wheel Colliders at wheel positions. Set radius (0.3-0.4m), suspension distance, and spring/damper.

Configure suspension

Set spring (35000), damper (4500), target position (0.5). Determines bump reaction.

Implement steering

Set front wheel steer angle based on input. Use Ackermann steering for realistic turns.

Apply engine force

Apply motor torque to drive wheels. Use a gear curve: low gears = high torque, high = high speed.

Add anti-roll bars

Stabilize the car by applying opposing forces to left/right wheels. Prevents flipping.

FluxScript Example

Here is a complete FluxScript implementation for this guide:

Vehicles — FluxScript

on start {
  car = scene.find("RaceCar")
  car.setRigidbody(true)
  car.setMass(1200)
  car.setCollider("box", { size: vec3(2, 0.5, 4) })
  car.setCenterOfMass(vec3(0, -0.3, 0))
  wheelPos = [vec3(-1,0,1.4), vec3(1,0,1.4), vec3(-1,0,-1.4), vec3(1,0,-1.4)]
  for i = 0 to 4 {
    car.addWheel(wheelPos[i], { radius: 0.35, suspensionSpring: 35000, friction: 1.8 })
  }
}

on update(dt) {
  car = scene.find("RaceCar")
  speed = car.getSpeed()
  steerFactor = math.clamp(1 - speed / 80, 0.3, 1.0)
  steer = 0
  if input("a") steer = -25 * steerFactor
  if input("d") steer = 25 * steerFactor
  car.setWheelSteer(0, steer)
  car.setWheelSteer(1, steer)
  motor = 0
  if input("w") motor = 800
  if input("s") motor = -400
  car.setWheelMotor(2, motor)
  car.setWheelMotor(3, motor)
  if input("space") {
    for i = 0 to 4 car.setWheelBrake(i, 3000)
  } else {
    for i = 0 to 4 car.setWheelBrake(i, 0)
  }
}

Node Graph Example

Prefer visual programming? Here is the equivalent Node Graph:

Vehicles — Node Graph

[On Start] --> [Set Rigidbody: mass=1200, CoM low]
   --> [Add 4 Wheels: radius=0.35, suspension springs]

[On Update] --> [Get Speed] --> [Calculate steerFactor]
   --> [Set Steer: front wheels (speed-scaled)]
   --> [Set Motor: rear wheels]
   --> [Branch: braking] --> [Set Brake: all/none]

Optimization Tips

Keep your implementation fast and efficient with these optimization tips:

Lower the center of mass to prevent flipping. Set CoM 0.2-0.4m below chassis center.
Reduce steering angle at high speed. Full steering at 150km/h causes spins. Scale inversely with speed.
Limit physics substeps for vehicles (8-12) for stable wheel simulation. Regular physics needs only 4-6.
Use anti-roll bars on both axles. Without them, cars flip easily in turns.