Car System not working, tryed everything [Files Provided]

I have been trying for almost 2 days now to get this working, but the car just falls into the ground to half of the wheels and it keeps erroring up to +999 times following line into the console:

NullReferenceException: Object reference not set to an instance of an object
UnityStandardAssets.Vehicles.Car.CarController.Move (Single steering, Single accel, Single footbrake, Single handbrake) (at Assets/Standard Assets/Vehicles/Car/Scripts/CarController.cs:136)
UnityStandardAssets.Vehicles.Car.CarUserControl.FixedUpdate () (at Assets/Standard Assets/Vehicles/Car/Scripts/CarUserControl.cs:27)

I have provided you a download link to my Project Folder, (Editor : Latest Beta)
I really need help with that car please, I tried literally everything to make it work.

Project Folder

The Wheel Meshes drop down menu in CarController was collapsed for me so I didn’t see the missing components.