JSFiddle - React, Tailwind, and code Playground

HTML

<input type="hidden" value="1" id="theValue" />
<div class="form-horizontal vehicleclass0">
    <select class="vehicleclass" name="contact['Vehicle0']">
        <option value="" style="color: #cecece !important;">--Vehicle type--</option>
        <option value="Car">Car</option>
        <option value="Truck">Truck</option>
        <option value="Boat">Boat</option>
        <option value="Tractor">Tractor</option>
    </select>
    <input type="text" class="vehicleclass" name="contact[Make-Model Vehicle0]" placeholder="Make/Model" autocapitalize="off">
</div>
<div id="myDiv"></div>
<a href="javascript:;" onclick="addElement();"><div class="addvehiclewrapper" id="plus">Add another vehicle</div></a>

CSS

.vehicleclass0 {
    margin-bottom: 5px;
}
.addvehiclewrapper {
    margin-top: 20px;
}

JavaScript

function addElement() {

      var ni = document.getElementById('myDiv');

      var numi = document.getElementById('theValue');

      var num = (document.getElementById('theValue').value - 1) + 2;

      numi.value = num;

      var newdiv = document.createElement('div');

      var divIdName = 'Vehicle ' + num + '';

      newdiv.setAttribute('id', divIdName);

      newdiv.innerHTML = '<div class="form-horizontal"><select class="vehicleclass" name="contact[' + divIdName + ']"><option value="" style="color: #cecece !important;">--Vehicle type--</option><option value="Car">Car</option><option value="Truck">Truck</option><option value="Boat">Boat</option><option value="Tractor">Tractor</option></select><input type="text" class="vehicleclass" name="contact[Make-Model ' + divIdName + ']" placeholder="Make/Model" autocapitalize="off"></div> <a href="" onclick="javascript:removeElement(' + divIdName + '); return false">Remove ' + divIdName + '</a>';

      ni.appendChild(newdiv);

  }