var makes = new Array();
  makes.push(new Array('Car', 'Alfa Romeo', '65'));
  makes.push(new Array('Car', 'Chevrolet', '68'));
  makes.push(new Array('Van', 'Daewoo', '22'));
  makes.push(new Array('Car', 'Daewoo', '89'));
  makes.push(new Array('Van', 'Dodge', '15'));
  makes.push(new Array('Car', 'Fiat', '87'));
  makes.push(new Array('Car', 'Ford', '112'));
  makes.push(new Array('Car', 'Honda', '72'));
  makes.push(new Array('Car', 'Hyundai', '98'));
  makes.push(new Array('Car', 'Kia', '77'));
  makes.push(new Array('Car', 'Mazda', '93'));
  makes.push(new Array('Van', 'Mitsubishi', '50'));
  makes.push(new Array('Car', 'Mitsubishi', '116'));
  makes.push(new Array('Car', 'Nissan', '115'));
  makes.push(new Array('Van', 'Peugeot', '24'));
  makes.push(new Array('Car', 'Peugeot', '91'));
  makes.push(new Array('Van', 'SsangYong', '43'));
  makes.push(new Array('Motorbike', 'Suzuki', '58'));
  makes.push(new Array('Van', 'Toyota', '7'));
  makes.push(new Array('Car', 'Toyota', '67'));
  makes.push(new Array('Van', 'Volkswagen', '17'));
  makes.push(new Array('Car', 'Volkswagen', '81'));
function vehicleSelected() {
  vehicle_type = $('vehicle_type').getValue();
  options = $('make').options;
  options.length = 0;
  options[options.length] = new Option('Todas', '', true);
  makes.each(function(make) {
    if (make[0] == vehicle_type) {
      options[options.length] = new Option(make[1], make[2]);
    }
  });
  //dejando modelo en blanco
  model_options = $('model').options;
  model_options.length = 0;
  model_options[model_options.length] = new Option('Todos', '', true);
}

document.observe('dom:loaded', function() {
  vehicleSelected();
  $('vehicle_type').observe('change', vehicleSelected);
});