Shifting gears can cause the client to not properly represent which gear the vehicle is currently engaged.

For instance. I would down shift into reverse, but the car would not respond as if it was in reverse. In some cases, the car would move forward during acceleration in reverse. Which can cause the engine light to come on and damage the spark plug. I have a video I'll up upload of this happening.

In other cases, I will put the car in neutral expecting the car to idle. But upon exiting the car, the engine shuts off. Then getting back into the car will show the car in a different gear than netural.