No route matches [POST] "/user/1/cars" - ruby-on-rails

Question

on my app i have this
i'm trying to create a car of a previously registered user
but i got the error (tittle post)
this is my carcontroller
class CarController < ApplicationController
def new
#car = Car.new
end
def create
#user = User.find(params[:user_id])
#car = #user.car.create(params[:car])
redirect_to user_path(#user)
end
end
this is my route.rb
Estaciones::Application.routes.draw do
devise_for :users
root :to => "user#index"
resources :user do
resources :cars
end
get "user/new"
post "user/create"
get "user/:id" => "User#show"
get "user/:user_id/car/new"
and this is part of my html.erb
<div class="container">
<h1>new user registered</h1>
<p>
<strong>name:</strong>
<%= #user.name %>
</p>
<p>
<strong>email:</strong>
<%= #user.email %>
</p>
<h2>new car registration</h2>
<%= form_for([#user, #user.car.build]) do |f| %>
<p>
<%= f.label :brand %><br />
<%= f.text_field :brand %>
</p>
<p>
<%= f.label :color %><br />
<%= f.text_field :color %>
</p>
<p>
<%= f.label :model %><br />
<%= f.text_field :model %>
</p>
<p>
<%= f.label :year %><br />
<%= f.text_field :year %>
</p>
<p>
<%= f.submit "Create new car"%>
</p>
<% end %>
</div>
when i submit the creation of the new car i got the next error
No route matches [POST] "/user/1/cars"
any idea??
also my routes:
new_user_session GET /users/sign_in(.:format) devise/sessions#new
user_session POST /users/sign_in(.:format) devise/sessions#create
destroy_user_session DELETE /users/sign_out(.:format) devise/sessions#destroy
user_password POST /users/password(.:format) devise/passwords#create
new_user_password GET /users/password/new(.:format) devise/passwords#new
edit_user_password GET /users/password/edit(.:format) devise/passwords#edit
PUT /users/password(.:format) devise/passwords#update
cancel_user_registration GET /users/cancel(.:format) devise/registrations#cancel
user_registration POST /users(.:format) devise/registrations#create
new_user_registration GET /users/sign_up(.:format) devise/registrations#new
edit_user_registration GET /users/edit(.:format) devise/registrations#edit
PUT /users(.:format) devise/registrations#update
DELETE /users(.:format) devise/registrations#destroy
root / user#index
user_cars GET /user/:user_id/cars(.:format) cars#index
POST /user/:user_id/cars(.:format) cars#create
new_user_car GET /user/:user_id/cars/new(.:format) cars#new
edit_user_car GET /user/:user_id/cars/:id/edit(.:format) cars#edit
user_car GET /user/:user_id/cars/:id(.:format) cars#show
PUT /user/:user_id/cars/:id(.:format) cars#update
DELETE /user/:user_id/cars/:id(.:format) cars#destroy
user_index GET /user(.:format) user#index
POST /user(.:format) user#create
new_user GET /user/new(.:format) user#new
edit_user GET /user/:id/edit(.:format) user#edit
user GET /user/:id(.:format) user#show
PUT /user/:id(.:format) user#update
DELETE /user/:id(.:format) user#destroy
user_new GET /user/new(.:format) user#new
user_create POST /user/create(.:format) user#create
GET /user/:id(.:format) User#show
GET /user/:user_id/cars/new(.:format) car#new

Answer 1

I am not a ruby on rails person. But....
your post url /users/1/cars does not match any of the routes you mentioned in your route.rb file.

Answer 2

Try to do this :
root :to => "user#index"
resources :users do
resources :cars
end
Instead this :
root :to => "user#index"
resources :user do
resources :cars
end
(add a s to user). And try to go here : /users/1/cars

Answer 3

The problem is because resources :user is singular, but the route wants a plural. The routes should be:
resources :users do
resources :cars
end