It might be a problem with $_ localization: look at line 3.

package Car;
sub new { bless {},shift };
sub title { $_='title'; 'BITTER' };
sub descr { 'BUTTER' };
sub F { ( Car->new, Car->new, Car->new, Car->new ) };

package main;
print map{{title=>$_->title(),desc=>$_->descr()}} Car->F();
use Data::Dumper;
die Dumper map{{title=>$_->title(),desc=>$_->descr()}} Car->F();
[download]

output: