@volkswin, your mother in law can ask for a price to buy the Tiguan at the end of the lease. I doubt they’d entertain anyone buying it before then. In general the price Motability asks is not competitive.
Just before a handed my previous lease back (2017 Skoda Superb SEL exec 190nhp) a couple of months ago I asked MB for a price. I can’t remember the exact figures but for a couple hundred less I could have got an identical car but on a 67 plate from the main dealers that would have come with a 12 month Skoda assured warranty and any minor car park dings repaired. MB sell at full retail price on a trade basis.