Looking at the documentation of Rose::DB::Object::Manager it seems that the get_$thing methods already return array references.

But since HTML::Template can't call methods, you have to turn each object into a hash reference first. So for example:

my $cars = YourClass->get_classes;
$cars = [map {; {name => $_->name, manufacturer => $_->manufacturer } 
+}, @$cars];

$template->param(cars => $cars);
[download]

(I'm not really familiar with RDOM, so take this with a grain of salt).

Of course it kinda defeats the purpose of an object-relation mapper to first construct objects, and then turn them into dumb hashes...