If your new home will have an attached garage , it's a good idea to insulate this area as well.
The wall between the garage and the interior of your home should be considered an exterior wall and insulated to the level of other exterior walls. An insulated garage door can dramatically reduce heat loss.
A well-insulated garage will also help keep your vehicles running smoothly during cold weather.
If you'll be using your garage as a workshop, you might consider investing in radiant floor heating. This option will provides better warmth, uses less energy and eliminates the safety hazards of a portable space heater. Ask your builder for more details.