use strict;
use warnings;
use XML::Twig;

my $twig= new XML::Twig(
    twig_handlers => { Vehicle => \&vehicle }
);
$twig->parsefile('in.xml');
exit;

sub vehicle {
    my ($twig, $car) = @_;
    return if $car->first_child('Summary');
    my $file = $car->first_child('AuctionID')->text() . '.csv';
    open my $fh, '>', $file or die "can not open $file: $!";
    print $fh "AuctionID,Ref,VehicleID,Manufacturer\n";
    print $fh join ','
        , $car->first_child('AuctionID'   )->text()
        , $car->first_child('Ref'         )->text()
        , $car->first_child('VehicleID'   )->text()
        , $car->first_child('Manufacturer')->text()
    ;
    print $fh "\n";
    close $fh;
}  

##</code><code>##

AuctionID,Ref,VehicleID,Manufacturer
25019,1480714,156171,TOYOTA