Each car has a unique identifying number, am not sure if each trim version has a unique number as well, it should really. Its a number the dealer enters into the Motability application which lets them know what is ordered.
Older and new models have different numbers.
E.g. merc CLA on the motability car search is something like 672103. If you call the dealership and give them the number, they can tell you what the MY25 or the model year number.
But generally, if its a cheap deal they are moving old stock until the newer model comes aling with a higher AP.