Database
[{linenumber:"car",type:"004",nested:{info:{subinfo:"B"}},},{linenumber:"car",type:"005",nested:{info:{subinfo:"G"}},}]
Query
db.collection.aggregate([{$match:{$and:[{linenumber:"car"},{nested:{info:{subinfo:{$in:["B","G"]}}}}]}},{$group:{_id:null,types:{$addToSet:"$type"}}}])