Model year (modelYearID) corresponds to the year that a group of vehicles in the fleet was produced. Calendar year (yearID) is the analysis year as selected in the ‘Time Spans/Year’ panel of the MOVES GUI. For a given calendar year, the newest vehicles in the fleet will be those produced in the selected calendar year (i.e., modelYearID=yearID).
The age of a vehicle is calculated as:
ageID = yearID – modelYearID.
For example, if you select ‘2018’ as your calendar year, then the ageFraction associated with yearID ‘2018’, ageID ‘3’, and sourceTypeID ‘21’ indicates the fraction of passenger cars in the fleet produced in 2015.