I replaced an old train by sending it to depot and:
Bought a new loco (train 12)
Sold the old loco (train 1 – 35 years old)
Moved the carriages from the old train 1 to the new train 12
After setting the line for train 12 the age of the train is still 35 years. How is the game tracking the age of rolling stock? Are the carriages counted somehow and if so how do they contribute to the running costs as they age? Is the reported age in the UI the age of the oldest item in the consist?