my $seen = 0;

my @carmakers;
while (<DATA>) {
  chop;
  my ($id, $maker, $make) = split(",", $_);
  if ($id != $seen) {
    my %maker;
    $maker{'thismaker'} = $maker;
      my @makes;
      my %make = ('thismake' => $make);
      push(@makes, \%make);
    $maker{'makes'} = \@makes;
    push(@carmakers, \%maker);  # problem1
    $seen = $id;
  } else {   
      my %make = ('thismake' => $make);
      push(@makes, \%make);  # problem2
    $maker{'makes'} = \@makes;
  }
}