Lifted from a web site:
Lockout.
Lockout is the fastest growing cause of Emergency Road Service calls. This is partly because modern car locks are so efficient. Not only can you lock all the doors at once on many cars, the locks are so good that everyone but thieves has a difficult time defeating them. And high-tech locks often also are high-fragility locks. Forget about the bent coat hanger as savior.
Prevention is simple and cheap:
• Carry a spare key in your wallet or purse. Don’t keep it in a jacket pocket—jackets often are left in cars. And don’t try to hide it in a wheel well or beneath the floorboards. Give those thieves a little credit.
Speaking of credit, AAA members can get a free Credit Card Key. Bring your membership card and car door key to any district office, where a spare Credit Card Key can be made in less than a minute. The spare key is the size, shape, and thickness of a credit card, so will fit easily into a wallet or purse. Note that Credit Card Keys aren’t available for some high-security lock systems and some unusual vehicles.
• Get into the habit of locking your car door with the key. This ensures you have it with you when the car is locked up.
• Write down the key code number and keep it in your wallet or purse. A locksmith may be able to make a new key using the number. The key code number sometimes can be found on a sticker in the glove box, sometimes in the car’s owner manual, sometimes on a metal tag accompanying the key, or you can ask the dealer.