creating criterions to group

Hi, I'm still working with grouped elements and my structure grow up,
demanding every time more and more

I'm still applying this  sample to count elements

<xsl:value-of select="count(car[generate-id(.) =  
 generate-id(key('by-model',isbn)[1])])" />

Remember this, my  XML structure:  

<cars> 
    <car> 		<model>V667320</model>
 		<name>Sportage</name>
                 <categ>sport</categ>
                  <color>grey</color>
                  <year>1999</year>
    </car>
    <car>
 		<model>M382932</model>
 		<name>Silverado</name>
                <categ>pick-up</categ>
                  <color>white</color>
                  <year>20001</year>
  </car>
  <car>
 		<model>L930389</model>
 		<name>Jaguar</name>
                 <categ>Sport</categ>
                  <color>red</color>
                  <year>1997</year>
   </car>
   <car>
 		<model>V667320</model>
 		<name>Sportage</name>
                 <categ>sport</categ>
                  <color>green</color>
                  <year>1999</year>
   </car>
 </cars>


My question  I don't know if xsl:key allows to select a element and a
predicate or anything similar. I've been trying to group the cars from
same model and now using intervals of years
to display a report,

some like this


model              1981-1985    1986-1990   1991-1995   1996-200

sportage                                                              
         1

Jaguar                                                                
           1


Can you instruct me ?

Thanks

Marcos Hercules dos Santos.