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my %cars = (
  1002 => {
...
  12 = "Camaro",
  27 = "RSX",
};

my %makes_idx = (
  1 => [1001, ... ],    # cars that are Chevys
  10 => [1002, ...],    # cars that are Acuras
  ... );

my %years_idx = (
  2001 => [ 1001, 1002, ... ], # cars that are 2001 models
  ... );

# For example, finding all 2001 or newer Chevys
my %temp_hash = reverse %makes;         # gives the id for each make
...
# search above for 2001 or newer models
my @temp_years = grep { $_ >= 2001 } keys %years_idx;
my @result_ids = grep { exists $make_set{$_} } @years_idx{@temp_years}
+;