You can argue whether or not having lights on in the daytime is safer or not. I think it is:
There is no sensor that will 'know' its cloudy or foggy and that lights will help you to be seen. Because of this, I am in the habit of driving with my lights on all the time.
The number one thing that annoys me about my current car (a Subaru) is that it assumes that if your lights are on, it must be night, and therefore it dims all of the controls. This means that in the daytime, I can't see the clock or any of the other 'dimmable' controls (radio station, etc.) unless I temporarily turn off the lights. "Is the A/C on? I don't know. Give me a minute while I cup my hands around the control to make it dark enough and then put my face right in front of the tiny orange LED which you can only see from straight-on over the console. I still can't tell. Let me turn it on and off a few times... yeah, I think that's on. Yes, there's definitly more drag on the engine... it must be on. Gosh... I've had a crash! Sorry officer. I was just trying to see if the A/C is on..."
Ok, I'll get to the point:
I just saw a video in which control of the lights of the Model S was demonstrated (on a beta). When you turn on the lights, the screen goes into 'night mode'. I would like to suggest that this change be made configurable. I don't want my car to be in 'night mode' all the time just because I want to have the lights on. I would suggest that if there is a light sensor in the car, that its output be used to determine night mode rather than using the lights on/off setting. If there is no sensor, at least have an easy way to leave the screen in 'day mode' even though the lights are on.
Having a car that 'knows you' is great. Having a car that thinks it knows you (and insists on having its way) is not.