解决！

我不知道到底发生了什么问题，但它运行良好：

 < persistence version = 2.0
 xmlns =http://java.sun.com/xml/ns/persistencexmlns：xsi =http://www.w3.org/2001/XMLSchema-instance
 xsi：schemaLocation =http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd\"> 

< persistence-unit name =defaulttransaction-type =RESOURCE_LOCAL> 
< provider> org.hibernate.ejb.HibernatePersistence< / provider> 

<属性> 
< property name =javax.persistence.jdbc.drivervalue =org.postgresql.Driver/> 
< property name =javax.persistence.jdbc.urlvalue =jdbc：postgresql：// localhost：5432 / Automoveis/> 
< property name =javax.persistence.jdbc.uservalue =postgres/> 
< property name =javax.persistence.jdbc.passwordvalue =1234/> 
< property name =hibernate.dialectvalue =org.hibernate.dialect.PostgreSQLDialect/> 
< property name =hibernate.hbm2ddl.autovalue =update/> 
< property name =hibernate.show_sqlvalue =true/> 
< property name =hibernate.format_sqlvalue =true/> 
< / properties> 
< / persistence-unit> 
 

Have put the persistence.xml in the classpath of the project in eclipse because before the error was that the file was not found. Now gives this error:

Caused by: javax.persistence.PersistenceException: Invalid persistence.xml. Error parsing XML [line : -1, column : -1] : cvc-elt.1: Can not find the declaration of element 'persistence'

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1"
             xsi:schemalocation="http://java.sun.com/xml/ns/persistence
                                 http://java.sun.com/xml/ns/persistence/persistence_2_1.xsd">
    <persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
            <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/Automoveis" />
            <property name="javax.persistence.jdbc.user" value="postgres" />
            <property name="javax.persistence.jdbc.password" value="1234" />
            <property name="javax.persistence.jdbc.driver" value="org.postgresql.jdbc.Driver" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
            <property name="hibernate.hbm2ddl.auto" value="create" />
        </properties>
    </persistence-unit>
</persistence>

Solved!

I do not know exactly what was wrong, but it worked well:

<persistence version="2.0"   
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">    

<persistence-unit name="default" transaction-type="RESOURCE_LOCAL">    
    <provider>org.hibernate.ejb.HibernatePersistence</provider>    

    <properties>    
        <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />    
        <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/Automoveis" />    
        <property name="javax.persistence.jdbc.user" value="postgres" />    
        <property name="javax.persistence.jdbc.password" value="1234" />    
        <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />               
        <property name="hibernate.hbm2ddl.auto" value="update" />    
        <property name="hibernate.show_sql" value="true" />    
        <property name="hibernate.format_sql" value="true"/>    
    </properties>    
</persistence-unit>