It would be even better if the mud on the car body were a bit heavier!
I discovered a few other minor issues: assigning just a single tractor is sufficient to harvest wood—there is no need to assign a transport vehicle or a feller-buncher. Even when specific vehicles are assigned to employees, work continues as normal, yet I am still able to use those assigned vehicles myself.
I think you could increase the recorded operating hours for the machines; it’s unrealistic for equipment returning from a job to still show zero hours of use. Adding operating hours—along with signs of dirt and paint damage—would enhance the playability. Please consider this idea.