When you shift to L, the + and - buttons are enabled. L in your Malibu functions as electronic range select mode. This mode allows you to pick the highest gear limit the transmission can use. The L you see on your driver information center when you shift to L will have a number after it. The number indicates the highest gear currently allowed. The transmission will shift between 1st gear and that number. For example, lets say you are in P and shift to L then tap + until it says L3. The car will now shift between 1st, 2nd, and 3rd gear automatically. Another example: lets say you are parked with the car on in P. If you shift to L, then tap the + until it says L6, the car will automatically shift between all forward gears since you have a 6-speed transmission. If you shift to L while driving, the car will shift one gear lower then you can adjust the max with the + and -. If you try and hit - too far for the given speed it will say shift denied.