These days, there are many different types of car keys. It was easy to replace the old fashioned metal keys, but car key replacements for many modern car models are hard to come by. It's a good idea to have a car key replacement on hand in case you lose the original. Make sure to keep your car key replacement in a secure place. If anyone gets their hands on it, your car is as good as theirs. Many people leave a key with a friend or family member so they can easily get it when they need it.