For your mats use the sort of T shaped attachment and wrap microfibres round it! Works a treat but you'll need a water extractor for that deep clean!
Works awesome on leather as the heat opens the pours for a deeper clean!
But yeah as above be weary of the damage it can cause. Not only melting plastics but the psi on delicate surfaces can cause damage. MINIs are fairly safe but VW's have this horrible coating like plasti dip on their plastics and it'll rip that clean off!