add basic structure

app/Models/Car.php

@@ -8,4 +8,48 @@ use Illuminate\Database\Eloquent\Model;
 class Car extends Model
 {
     use HasFactory;
+
+    protected $fillable = [
+        'variation',
+        'variation',
+        'vin',
+        'colour',
+        'notes',
+        'known_damage',
+        'initial_date',
+        'bought_at',
+        'buy_price',
+        'seller_contact_id',
+        'car_model_id'
+    ];
+
+    public function brand()
+    {
+        return $this->hasOneThrough(Brand::class, CarModel::class);
+    }
+
+    public function carModel()
+    {
+        return $this->belongsTo(CarModel::class);
+    }
+
+    public function seller()
+    {
+        return $this->belongsTo(Contact::class, 'seller_contact_id');
+    }
+
+    public function buyer()
+    {
+        return $this->hasOneThrough(Contract::class, Contact::class);
+    }
+
+    public function contract()
+    {
+        return $this->hasOne(Contract::class);
+    }
+
+    public function carPayment()
+    {
+        return $this->hasManyThrough(CarPayment::class, Contract::class);
+    }
 }