A roof over your equipment is more than shelter.

Owned vehicles and implements that are parked outdoors slowly get dirty and take small amounts of damage over in-game time. If rain or snow is falling, outdoor dirt builds up faster and outdoor damage increases more quickly.

Equipment parked under a roof is protected from outdoor wear. Optional Auto Wash and Auto Repair settings can also let covered equipment clean and repair itself over time, but only on land owned by the vehicle's farm. Auto Repair has a configurable cost, defaulting to 125% of the normal repair price.