diff --git a/docs/web/docs/Definition_of_Vehicles,_Vehicle_Types,_and_Routes.md b/docs/web/docs/Definition_of_Vehicles,_Vehicle_Types,_and_Routes.md
index 2fd7586784b2..5be54f157809 100644
--- a/docs/web/docs/Definition_of_Vehicles,_Vehicle_Types,_and_Routes.md
+++ b/docs/web/docs/Definition_of_Vehicles,_Vehicle_Types,_and_Routes.md
@@ -487,6 +487,7 @@ startupDelay        | float >= 0        | 0                | The extra delay tim
 | guiShape          | shape (enum)                      | "unknown"                                                           | [a vehicle shape for drawing](#visualization). By default a standard passenger car body is drawn.                                                                                                           |
 | width             | float                             | 1.8                                                                 | The vehicle's width \[m\] (used only for visualization with the default model, affects [sublane model](Simulation/SublaneModel.md))                                                                            |
 | height            | float                             | 1.5                                                                 | The vehicle's height \[m\]                                                                            |
+| mass              | float                             | 1500                                                                | The vehicle's empty mass \[kg\]                    |
 | collisionMinGapFactor | float                             | depends on carFollowModel (1.0 for most models)                                                                | The minimum fraction of minGap that must be maintained to the leader vehicle to avoid a collision event                                                                            |
 | imgFile           | filename (string)                 | ""                                                                  | Image file for rendering vehicles of this type (should be grayscale to allow functional coloring)                                                                                                                      |
 | osgFile           | filename (string)                 | ""                                                                  | Object file for rendering with OpenSceneGraph (any of the file types supported by the available OSG-plugins)                                                                                                           |