public class WrapperClass {   
    
    public class VehicleWrapper {
        @AuraEnabled
        public String MakeId {get;set;}
        @AuraEnabled
        public String MakeName {get;set;}
        @AuraEnabled
        public String VehicleTypeId {get;set;}
        @AuraEnabled
        public String VehicleTypeName {get;set;}
    }

public with sharing class DPLightningHandler {

    @AuraEnabled
    public static List < WrapperClass.VehicleWrapper > fetchInventory(String vehicleMake) {
        List < WrapperClass.VehicleWrapper > listVehicles = new List < WrapperClass.VehicleWrapper >();
        HTTPRequest req = new HTTPRequest();
        req.setEndPoint('https://vpic.nhtsa.dot.gov/api/vehicles/GetVehicleTypesForMake/' + vehicleMake + '?format=json');
        req.setMethod('GET');
        HTTP objHTTP = new HTTP();
        HTTPResponse res = objHTTP.send(req);
        system.debug('Response is ' + res.getBody());
        JSONParser parser = JSON.createParser(res.getBody());
        System.JSONToken token;
        String text;
        parser.nextToken(); // Eat first START_OBJECT {
        parser.nextToken(); // Eat token = FIELD_NAME; text = postalcodes
        parser.nextToken(); // Eat first START_ARRAY [
        parser.nextToken(); // Eat the first object's START_OBJECT {
        WrapperClass.VehicleWrapper obj;
        while ( ( token = parser.nextToken()) != null ) {
            if ( ( token = parser.getCurrentToken() ) != JSONToken.END_OBJECT ) {
                text = parser.getText();
                if ( token == JSONToken.FIELD_Name && text == 'MakeId' ) {
                    token = parser.nextToken();
                    obj = new WrapperClass.VehicleWrapper();
                    obj.MakeId = parser.getText();
                } else if (token == JSONToken.FIELD_Name && text == 'MakeName' ) {
                    token = parser.nextToken();
                    obj.MakeName = parser.getText();
                } else if ( token == JSONToken.FIELD_Name && text == 'VehicleTypeId' ) { 
                    token = parser.nextToken();
                    obj.VehicleTypeId = parser.getText();
                } else if ( token == JSONToken.FIELD_Name && text == 'VehicleTypeName' ) {
                    token = parser.nextToken();
                    obj.VehicleTypeName = parser.getText();
                    listVehicles.add(obj);
                } 
            } 
        }
        system.debug('listVehicles are ' + listVehicles);
        return listVehicles;
    }
    
}