diff --git a/internal/model/model_car.go b/internal/model/model_car.go
index 075bd25..9449792 100644
--- a/internal/model/model_car.go
+++ b/internal/model/model_car.go
@@ -3,14 +3,16 @@ package model
 import (
 	"errors"
 
+	"fmt"
 	"net/http"
+	"strconv"
 
 	"github.com/manyminds/api2go"
 	"github.com/manyminds/api2go/jsonapi"
 )
 
 type Car struct {
-	ID      string `json:"-"`
+	ID      uint64 `json:"-"`
 	Brand   string `json:"brand"`
 	Model   string `json:"model"`
 	Price   uint64 `json:"price"`
@@ -70,12 +72,16 @@ func newVerifyError(title string, detail string, pointer string) api2go.Error {
 
 // GetID to satisfy jsonapi.MarshalIdentifier interface
 func (c Car) GetID() string {
-	return c.ID
+	return fmt.Sprintf("%d", c.ID)
 }
 
 // SetID to satisfy jsonapi.UnmarshalIdentifier interface
 func (c *Car) SetID(id string) error {
-	c.ID = id
+	intID, err := strconv.ParseUint(id, 10, 64)
+	if err != nil {
+		return err
+	}
+	c.ID = intID
 	return nil
 }
 
diff --git a/internal/resource/resource_car.go b/internal/resource/resource_car.go
index b264c29..3f6ab08 100644
--- a/internal/resource/resource_car.go
+++ b/internal/resource/resource_car.go
@@ -3,7 +3,7 @@ package resource
 import (
 	"errors"
 	"net/http"
-	"sort"
+	_ "sort"
 	"strconv"
 
 	"go-jsonapi-example/internal/model"
@@ -19,17 +19,11 @@ type CarResource struct {
 
 // FindAll to satisfy api2go data source interface
 func (s CarResource) FindAll(r api2go.Request) (api2go.Responder, error) {
-	cars := s.CarStorage.GetAll()
-	result := make([]model.Car, 0, len(cars))
-
-	for _, car := range cars {
-		result = append(result, *car)
-	}
-
-	return &Response{Res: result}, nil
+	return &Response{Res: s.CarStorage.GetAll()}, nil
 }
 
 // PaginatedFindAll can be used to load cars in chunks
+/*
 func (s CarResource) PaginatedFindAll(r api2go.Request) (uint, api2go.Responder, error) {
 	var (
 		result                      []model.Car
@@ -104,10 +98,15 @@ func (s CarResource) PaginatedFindAll(r api2go.Request) (uint, api2go.Responder,
 
 	return uint(len(cars)), &Response{Res: result}, nil
 }
-
+*/
 // FindOne to satisfy `api2go.DataSource` interface
 func (s CarResource) FindOne(ID string, r api2go.Request) (api2go.Responder, error) {
-	car, err := s.CarStorage.GetOne(ID)
+	intID, err := strconv.ParseUint(ID, 10, 64)
+	if err != nil {
+		return &Response{}, api2go.NewHTTPError(err, err.Error(), http.StatusNotFound)
+	}
+
+	car, err := s.CarStorage.GetOne(intID)
 	if err != nil {
 		return &Response{}, api2go.NewHTTPError(err, err.Error(), http.StatusNotFound)
 	}
@@ -133,7 +132,10 @@ func (s CarResource) Create(obj interface{}, r api2go.Request) (api2go.Responder
 
 // Delete to satisfy `api2go.DataSource` interface
 func (s CarResource) Delete(id string, r api2go.Request) (api2go.Responder, error) {
-	err := s.CarStorage.Delete(id)
+	intID, err := strconv.ParseUint(id, 10, 64)
+	if err == nil {
+		err = s.CarStorage.Delete(intID)
+	}
 	return &Response{Code: http.StatusNoContent}, err
 }
 
diff --git a/internal/storage/storage_car.go b/internal/storage/storage_car.go
index 2a9929d..f6264d4 100644
--- a/internal/storage/storage_car.go
+++ b/internal/storage/storage_car.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"sync"
 
 	"go-jsonapi-example/internal/model"
 
@@ -11,36 +12,55 @@ import (
 )
 
 type CarStorage struct {
-	cars    map[string]*model.Car
-	idCount int
+	mutex   sync.RWMutex
+	cars    map[uint64]*model.Car
+	idCount uint64
 }
 
+type Cars []model.Car
+
+func (c Cars) Len() int           { return len(c) }
+func (c Cars) Swap(i, j int)      { c[i], c[j] = c[j], c[i] }
+func (c Cars) Less(i, j int) bool { return c[i].ID < c[j].ID }
+
 func NewCarStorage() *CarStorage {
-	return &CarStorage{make(map[string]*model.Car), 1}
+	return &CarStorage{cars: make(map[uint64]*model.Car), idCount: 1}
 }
 
-func (s CarStorage) GetAll() map[string]*model.Car {
-	return s.cars
-}
-
-func (s CarStorage) GetOne(id string) (model.Car, error) {
-	user, ok := s.cars[id]
-	if ok {
-		return *user, nil
+func (s CarStorage) GetAll() Cars {
+	s.mutex.RLock()
+	defer s.mutex.RUnlock()
+	result := make(Cars, 0, len(s.cars))
+	for _, car := range s.cars {
+		result = append(result, *car)
 	}
+	return result
+}
+
+func (s CarStorage) GetOne(id uint64) (model.Car, error) {
+	s.mutex.RLock()
+	car, ok := s.cars[id]
+	if ok {
+		defer s.mutex.RUnlock()
+		return *car, nil
+	}
+	s.mutex.RUnlock()
 	errMessage := fmt.Sprintf("Car for id %s not found", id)
 	return model.Car{}, api2go.NewHTTPError(errors.New(errMessage), errMessage, http.StatusNotFound)
 }
 
-func (s *CarStorage) Insert(c model.Car) string {
-	id := fmt.Sprintf("%d", s.idCount)
-	c.ID = id
-	s.cars[id] = &c
+func (s *CarStorage) Insert(c model.Car) uint64 {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	c.ID = s.idCount
+	s.cars[s.idCount] = &c
 	s.idCount++
-	return id
+	return c.ID
 }
 
-func (s *CarStorage) Delete(id string) error {
+func (s *CarStorage) Delete(id uint64) error {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
 	_, exists := s.cars[id]
 	if !exists {
 		return fmt.Errorf("Car with id %s does not exist", id)
@@ -51,6 +71,8 @@ func (s *CarStorage) Delete(id string) error {
 }
 
 func (s *CarStorage) Update(c model.Car) error {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
 	_, exists := s.cars[c.ID]
 	if !exists {
 		return fmt.Errorf("Car with id %s does not exist", c.ID)