Fuel saving idea
 

How hard would this be to implement?

When the headlights switch is in the on position the headlights would only be on if the vehicle was moving. They would turn off when the vehicle was not moving. Only the parking lights would stay on. some sort of relay hooked into the VSS (Vehicle speed sensor). An override switch would allow you to keep them on at all times. I already shut the engine off at traffic lights but I am too busy turning the car on and getting into gear to deal with another powering up another system everytime.

You forget about cops???

You will get a ticket if your lights are off at night, it doesn't matter if the car is moving or standing still. Even if you get pulled over your lights are to remain on at night. I know this from personal experience.

Not to mention everyone(yourself included) having to redevelope their night vision everytime you turn them on/off.
Best to leave the lights on when the car is being used at night.

The best solution for this is to replace all the bulbs with LED's. On my last car I replaced all the bulbs in the back of the car(license lights, all braking lights, and etc.) This will lower the load. If you want to go the extra mile then replace all your dash bulbs to LED's. At night not only your lights are turned on(front and back) but your whole dash and instrument cluster is lit up.

There are no LED replacements for headlights.

I know, that is why I didn't mention that.

If you read his original question, it was about headlights.

The rear lights come on automatically when you turn on the headlights. Since he can't turn off the head lights at night he can lower the load on all his rear lights by switching to LED's.

Put a bunch of LEDs in the headlight when on the parking light setting and have them go on with the parking lights and stay on all the time the headlights are on also. If a headlight goes out you still have the LEDs as a backup for safety. When you come to a stop you can turn off the headlights but leave the parking lights and the Headlight LEDs on. Having them at least lit with the LEDs may cover you for them being on.

the biggest problem i see is its' dark you hop in your car, start it up and CRAP, you gotta start driving before you can see if there's anything infront ya ;)