<xsl:template match="z:row">
<xsl:element name="Cars">
<xsl:apply-templates select="z:row"/>
</xsl:element>
</xsl:template>
A z:row element does not have any children called z:row, so this apply-templates will select nothing.
You want <apply-templates select="@*"/>.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference