Mongo.db query that resolves just one element


I’m trying to get output one single number, based on the carNum value.
I have the following database

addCar: function(carNum, regDate, mark, model, consump, fuelCost, owner){
	throw new Meteor.Error('No access: You are not logged in.');

userId: Meteor.userId(),
owner: owner,
createdAt: new Date(),
carNum: carNum,
fuelCost: fuelCost,
regDate: regDate,
mark: mark,
model: model,
consump: consump



for example I have an element already added with carNum of 537.
Now I want that to look up the car with num 537 and resolve it’s fuelCost or consumption.
This query doesn’t work sadly.

var car = "537";
var fuelCost = Car.find({"carNum": {$eq: car}}, {fields: {'fuelCost':1}, limit:1});

console.log("Fuel cost "+fuelCost);


var fuelCost = Cars.findOne({"carNum" : {$eq: car}}, {fields: {fuelCost:1}, sort: {createdAt: -1}, limit: 1}).fuelCost;