use strict;
use warnings;
use Data::Dumper;

my %data;
while (<DATA>) {
    chomp;
    my ($lot, undef, $make, undef, $city, $state) = split /,/;
    $data{$lot}{$make}++;
    $data{$lot}{location} = "$city,$state";
}
print Dumper(\%data);

__DATA__
lot1,new,honda,civic,cincinnati,oh
lot1,used,chevy,impala,cincinnati,oh
lot1,new,honda,civic,cincinnati,oh
lot1,used,chevy,impala,cincinnati,oh
lot1,new,cadillac,escalade,cincinnati,oh
lot2,new,buick,sentry,houston,tx
lot2,used,ford,ranger,houston,tx
lot2,new,buick,sentry,houston,tx
lot2,used,ford,ranger,houston,tx
lot2,used,ford,ranger,houston,tx
lot3,new,ford,ranger,lexington,ky
lot3,used,cadillac,escalade,lexington,ky
lot3,used,cadillac,escalade,lexington,ky
lot4,new,ford,f150,chicago,illinois
lot4,new,ford,f150,chicago,illinois
lot4,new,ford,f150,chicago,illinois