stk-code_catmod/data/gfx/nitro-smoke.xml

<?xml version="1.0"?>
<particles emitter="box" box_x="0.35" box_y="0.2" box_z="0.2">

    <spreading angle="30"         />
    
    <velocity  x="0.0"
               y="0.0"
               z="-0.006"         />
    
    <material  file="smoke_nitro.png"  />
    
    <!-- Amount of particles emitted per second -->
    <rate      min="500"
               max="800"          />
    
    <!-- Minimal and maximal lifetime of a particle, in milliseconds. -->
    <lifetime  min="100"
               max="150"          />
    
    <!-- Size of the particles -->
    <size      min="0.20"
               max="0.40"         />
    
    <color     min="255 255 255"
               max="255 255 255"  />

</particles>