You can create a recursive function like this to do a depth-first traversal of the cars
object.
var findObjectByLabel = function(obj, label) {
if(obj.label === label) { return obj; }
for(var i in obj) {
if(obj.hasOwnProperty(i)){
var foundLabel = findObjectByLabel(obj[i], label);
if(foundLabel) { return foundLabel; }
}
}
return null;
};
which can be called like so
findObjectByLabel(car, "Chevrolet");