What I've come up with playing around trying to dynamically instantiate a class based on input. For example create a Car class if the name of the vehicle is a car's name.

dynamic_class_instantiation.rb

module Vehicle

  @@catigories = {
    car:   ["Focus", "Dart", "Civic"],
    truck: ["F150", "Super Duty"],
    van:   ["Caravan", "Town and Country"],
  }

  def self.category(name)
    @@catigories.each do |k,v|
      return k.capitalize if v.include? name
    end
    nil # return nill if we didn't find it
  end

  def self.new(name)
    if const_defined? category(name)
      klass = const_get category(name)
    else
      klass = const_set category(name), Class.new
    end
    klass.send(:include, self)
    klass.new name
  end

  attr_reader :name

  def initialize(name)
    @name = name
  end

  def jump_start!
    puts "Damn it, can't jump #{name}"
  end

end

class Car
  def boost(amount)
    puts "Zip Zap Zoom, #{name} boosts to level #{amount}"
  end
end

car   = Vehicle.new "Focus"
truck = Vehicle.new "F150"
van   = Vehicle.new "Caravan"

car.jump_start!   # will work
truck.jump_start! # will work

car.boost(1337) # will work
truck.boost(31) # will error