Marie the best way that I have found to lock your bike to your vehicle using a trunk rack is to purchase a seperate cable lock and use the tow loops that are typically on the bottom of your vehicles bumper. run the cable through the loops on the vehicle and then through the frame and wheels if possible. Typically the persin is trying to steal the bike. If you just want to leave the rack on the vehicle, there is no good solution, but the rack folds down in seconds and can be put into the back seat or in the trunk. Yakima does offer a new rack called a Quickback that does come with a security cable that i attached to the rack and when you put the other end of it into the trunk or hatchback, secures the rack to the vehicle. This is a brand new rack and is also the most simple rack to put on and take off a vehicle. This may be something for you to look into.