Database
[{"platformId":"CMC_123","carInfo":[["Toyota",20,"White"],["Suzuki",19,"Gray"],["Ford",22,"Red"]]}]
Query
db.collection.aggregate([{$match:{platformId:"CMC_123"}},{$project:{carMilage:{"$arrayToObject":{$map:{input:"$carInfo",in:{k:{$arrayElemAt:["$$this",0]},v:{$arrayElemAt:["$$this",1]}}}}}}}])