my $pq = PerlUser->new();
$pq->car( Car->new(type => 'random') );
my $fuel = $pq->car()->type_of_fuel();
my %fuels = (qw/Super Normal Normal Diesel Diesel Super/);
$fuel = exists $fuels{$fuel} ? $fuels{$fuel} : [keys %fuels]->[rand scalar(keys %fuels)];
$pq->car()->refuel($fuel);