A setting that displays the current vehicle speed in the vehicle information window.
Once this patch is activated, you'll know at any time how fast your vehicle is moving. The speed will be either displayed in km/h or mph, depending on your settings. You can change the distance units in the Game options window.
This feature is enabled by default. You can disable it through the configure patches -> interface window or use the following syntax in Openttd.cfg:
[patches] vehicle_speed = false