if you wanted to write your own xml's, there's an example
<configs>
<append xpath="/items">
<item name="M35A2Truck">
<property name="Extends" value="vehicleMinibikePlaceable"/>
<property name="CustomIcon" value="M35A2Truck"/>
<property name="DescriptionKey" value="vehicleGuppyMilitaryTruckDesc"/>
<property name="Meshfile" value="#@modfolder:Resources/GuppyMobiles.unity3d?guppyMilitaryTruck.prefab"/>
<property name="EconomicValue" value="40000"/>
<property class="Action1">
<property name="Vehicle" value="vehicleGuppyMilitaryTruck"/>
<property name="VehicleSize" value="2.5, 2.1, 5"/>
</property>
<effect_group name="Base Effects">
<passive_effect name="DegradationMax" operation="base_set" value="3500,7500" tier="1,6"/>
</effect_group>
</item>
<item name="Hummer">
<property name="Extends" value="vehicleMinibikePlaceable"/>
<property name="CustomIcon" value="Hummer"/>
<property name="DescriptionKey" value="vehicleGuppyMilitaryCarDesc"/>
<property name="Meshfile" value="#@modfolder:Resources/GuppyMobiles.unity3d?guppyMilitaryCar.prefab"/>
<property name="EconomicValue" value="40000"/>
<property class="Action1">
<property name="Vehicle" value="vehicleGuppyMilitaryCar"/>
<property name="VehicleSize" value="2.5, 2.1, 5"/>
</property>
<effect_group name="Base Effects">
<passive_effect name="DegradationMax" operation="base_set" value="3500,7500" tier="1,6"/>
</effect_group>
</item>
</append>
</configs>