diff --git a/jsprit-core/src/main/java/jsprit/core/problem/vehicle/VehicleImpl.java b/jsprit-core/src/main/java/jsprit/core/problem/vehicle/VehicleImpl.java
index 2692a24d..3f40b3f1 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/vehicle/VehicleImpl.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/vehicle/VehicleImpl.java
@@ -94,12 +94,14 @@ public class VehicleImpl implements Vehicle {
 		}
 		
 		/**
-		 * Sets the {@link VehicleType}.
+		 * Sets the {@link VehicleType}.<br>
 		 * 
 		 * @param type
+		 * @throws IllegalStateException if type is null
 		 * @return this builder
 		 */
 		public Builder setType(VehicleType type){
+			if(type==null) throw new IllegalStateException("type cannot be null.");
 			this.type = type;
 			return this;
 		}
@@ -166,6 +168,9 @@ public class VehicleImpl implements Vehicle {
 		/**
 		 * Builds and returns the vehicle.
 		 * 
+		 * <p>if {@link VehicleType} is not set, default vehicle-type is set with id="default" and 
+		 * capacity=0
+		 * 
 		 * @return vehicle
 		 * @throw IllegalStateException if both locationId and locationCoord is not set
 		 */
@@ -189,6 +194,8 @@ public class VehicleImpl implements Vehicle {
 	/**
 	 * Returns empty/noVehicle which is a vehicle having no capacity, no type and no reasonable id.
 	 * 
+	 * <p>NoVehicle has id="noVehicle" and extends {@link VehicleImpl}
+	 * 
 	 * @return emptyVehicle
 	 */
 	public static NoVehicle createNoVehicle(){
@@ -219,9 +226,14 @@ public class VehicleImpl implements Vehicle {
 		returnToDepot = builder.returnToDepot;
 	}
 	
+	/**
+	 * Returns String with attributes of this vehicle
+	 * 
+	 * <p>String has the following format [attr1=val1][attr2=val2]...[attrn=valn]
+	 */
 	@Override
 	public String toString() {
-		return "[id="+id+"][type="+type+"][locationId="+locationId+"][coord=" + coord + "]";
+		return "[id="+id+"][type="+type+"][locationId="+locationId+"][coord=" + coord + "][isReturnToDepot=" + isReturnToDepot() + "]";
 	}
 
 	public Coordinate getCoord() {
diff --git a/jsprit-core/src/test/java/jsprit/core/problem/vehicle/VehicleImplTest.java b/jsprit-core/src/test/java/jsprit/core/problem/vehicle/VehicleImplTest.java
new file mode 100644
index 00000000..5f3fa4cd
--- /dev/null
+++ b/jsprit-core/src/test/java/jsprit/core/problem/vehicle/VehicleImplTest.java
@@ -0,0 +1,102 @@
+package jsprit.core.problem.vehicle;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+import jsprit.core.problem.vehicle.VehicleImpl.NoVehicle;
+import jsprit.core.util.Coordinate;
+
+import org.junit.Test;
+
+
+public class VehicleImplTest {
+	
+	@Test
+	public void whenSettingTypeWithBuilder_typeShouldBeSet(){
+		VehicleType type = mock(VehicleType.class);
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationId("loc").setType(type).build();
+		assertEquals(type,v.getType());
+	}
+	
+	@Test(expected=IllegalStateException.class)
+	public void whenTypeIsNull_itThrowsIllegalStateException(){
+		@SuppressWarnings("unused")
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationId("loc").setType(null).build();
+	}
+	
+	@Test
+	public void whenTypeIsNotSet_defaultTypeIsSet(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationId("loc").build();
+		assertEquals("default",v.getType().getTypeId());
+		assertEquals(0,v.getType().getCapacity());
+	}
+	
+	@Test(expected=IllegalStateException.class)
+	public void whenVehicleIsBuiltWithoutSettingNeitherLocationNorCoord_itThrowsAnIllegalStateException(){
+		@SuppressWarnings("unused")
+		Vehicle v = VehicleImpl.Builder.newInstance("v").build();
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltAndReturnToDepotFlagIsNotSet_itShouldReturnToDepot(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationId("loc").build();
+		assertTrue(v.isReturnToDepot());
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltToReturnToDepot_itShouldReturnToDepot(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setReturnToDepot(true).setLocationId("loc").build();
+		assertTrue(v.isReturnToDepot());
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltToNotReturnToDepot_itShouldNotReturnToDepot(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setReturnToDepot(false).setLocationId("loc").build();
+		assertFalse(v.isReturnToDepot());
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltWithLocation_itShouldHvTheCorrectLocation(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationId("loc").build();
+		assertEquals("loc",v.getLocationId());
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltWithCoord_itShouldHvTheCorrectCoord(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationCoord(Coordinate.newInstance(1, 2)).build();
+		assertEquals(1.0,v.getCoord().getX(),0.01);
+		assertEquals(2.0,v.getCoord().getY(),0.01);
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltAndEarliestStartIsNotSet_itShouldSetTheDefaultOfZero(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationCoord(Coordinate.newInstance(1, 2)).build();
+		assertEquals(0.0,v.getEarliestDeparture(),0.01);
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltAndEarliestStartSet_itShouldBeSetCorrectly(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setEarliestStart(10.0).setLocationCoord(Coordinate.newInstance(1, 2)).build();
+		assertEquals(10.0,v.getEarliestDeparture(),0.01);
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltAndLatestArrivalIsNotSet_itShouldSetDefaultOfDoubleMaxValue(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLocationCoord(Coordinate.newInstance(1, 2)).build();
+		assertEquals(Double.MAX_VALUE,v.getLatestArrival(),0.01);
+	}
+	
+	@Test
+	public void whenVehicleIsBuiltAndLatestArrivalIsSet_itShouldBeSetCorrectly(){
+		Vehicle v = VehicleImpl.Builder.newInstance("v").setLatestArrival(30.0).setLocationCoord(Coordinate.newInstance(1, 2)).build();
+		assertEquals(30.0,v.getLatestArrival(),0.01);
+	}
+	
+	@Test
+	public void whenNoVehicleIsCreate_itShouldHvTheCorrectId(){
+		Vehicle v = VehicleImpl.createNoVehicle();
+		assertTrue(v instanceof NoVehicle);
+		assertEquals("noVehicle",v.getId());
+	}
+	
+
+}