Database
[{"make":"ford","VehicleImages":[{"image":"stuff5","ShowOrder":5},{"image":"stuff2","ShowOrder":2},{"image":"stuff3","ShowOrder":3},{"image":"stuff1","ShowOrder":1},{"image":"stuff4","ShowOrder":4}]},{"make":"vahxhall","VehicleImages":[{"image":"stuff2","ShowOrder":2},{"image":"stuff1","ShowOrder":1},{"image":"stuff4","ShowOrder":4},{"image":"stuff5","ShowOrder":5},{"image":"stuff3","ShowOrder":3}]}]
Query
db.collection.aggregate([{$set:{VehicleImages:{$sortArray:{input:"$VehicleImages",sortBy:{ShowOrder:1}}}}}])