Ordenação de colunas no primeFaces

Programação Java
#1

Galera,
Bom dia !!

Sou novo em java e estou trabalhando com JSF+PrimeFaces e me surgiu uma dúvida em relação ao sortBy numa coluna DataTable conforme código abaixo:

<ui:composition template="/WEB-INF/template/template.xhtml"
	xmlns:h="http://java.sun.com/jsf/html"
	xmlns:ui="http://java.sun.com/jsf/facelets"
	xmlns:f="http://java.sun.com/jsf/core"
	xmlns:p="http://primefaces.org/ui">
	<ui:define name="conteudo">
		<h1>Google App Engine + JSF 2.0 example + Primefaces+</h1>
	
	<p:layout fullPage="true">  
	<p:layoutUnit position="north" size="400" header="Listagem de Itens Glosados" resizable="true" closable="true" collapsible="true">	
		<h:outputText value="Nome:" /> <p:inputText> </p:inputText>
		<h:outputText value="Data Nascimento:" /> <p:inputText></p:inputText> <h:outputText value="Sexo" /> <p:inputText> </p:inputText>
		<h:outputText value="CPF:" /> <p:inputText></p:inputText> <h:outputText value="Idade:" /> <p:inputText></p:inputText>

    </p:layoutUnit>  
	
	<p:layoutUnit position="center">  

	<h:form id="form">
			
	
			<p:dataTable id="cars" var="car" value="#{tableMB.smallCarsModel}"
                 paginator="#{config['dataTable.paginator']}" rows="#{config['dataTable.rows']}"
                 rowKey="#{car.model}"
                 paginatorTemplate="{CurrentPageReport}  {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}"
                 rowsPerPageTemplate="#{config['dataTable.rowsPerPageTemplate']}" selection="#{tableMB.selectedCars}"
			selectionMode="multiple">
			
			<p:column style="width:2%">  
    			<p:rowToggler />  
			</p:column>  

			<p:column sortBy= "#{car.model}" headerText="Model" fil>
           		 #{car.model}
       	    </p:column>
			
			<p:column sortBy= "#{car.year}" headerText="Year">
          		 #{car.year}
            </p:column>

			<p:column sortBy= "#{car.manufacturer}" headerText="Manufacturer">
          		 #{car.manufacturer}
            </p:column>

			<p:column sortBy= "#{car.color}"  headerText="Color">
         		 #{car.color}
            </p:column>
            
            <p:rowExpansion>
            
            <h:panelGrid id="display" columns="2" cellpadding="4" style="width:500px;"
                            styleClass=" ui-widget-content grid">

                <h:outputText value="Model:" />
                <h:outputText id="model" value="#{car.model}" />

                <h:outputText value="Year:" />
                <h:outputText id="year" value="#{car.year}" />

                <h:outputText value="Manufacturer:" />
                <h:outputText value="#{car.manufacturer}"/>

                <h:outputText value="Color:" />
                <h:outputText value="#{car.color}"/>
            </h:panelGrid>

       		</p:rowExpansion>

			</p:dataTable>
		</h:form>
		</p:layoutUnit>
		</p:layout>
	</ui:define>
</ui:composition>

Gostaria de saber como ordenar apenas a coluna que estou selecionando, neste caso sem afetar as outras colunas.
EX: tenho as colunas year, model e color, desejo ordenar year e color e não ordenar a coluna model e vice-versa.

Desde já agradeço a colaboração de todos

#2