completing TODO parts.

src/main/java/org/model/GasCar.java

@@ -29,11 +29,44 @@ public class GasCar extends Car implements Refuelable {
 
     // TODO: Override getEnergyType() → return fuelType + " (Gas)"
 
+    @Override
+    public String getEnergyType() {
+        return fuelType +" (gas)";
+    }
+
     // TODO: Implement refuel(double amount)
     // Validate amount
     // Cap at 100
-
+    public void refuel(double amount){
+        if(amount < 0)
+            System.out.println("amount unacceptable");
+        else{
+            if (fuelLevel + amount > 100)
+                fuelLevel = 100;
+            else
+                fuelLevel += amount;
+        }
+    }
     // TODO: Override showDetails()
     // Call super.showDetails()
     // Print fuel level and fuel type
+
+    @Override
+    public void showDetails() {
+        super.showDetails();
+        System.out.println(" | fuelLevel: " + fuelLevel + " | fuel type: " + fuelType);
+    }
+
+    @Override
+    public boolean needsService(Vehicle v) {
+        return getMileage() > 12000;
+    }
+
+    @Override
+    public void performService() {
+        super.performService();
+        System.out.println("engine and oil checked");
+        this.fuelLevel = 100;
+
+    }
 }