When it comes to turning off interior lights when a door is open, there are several simple steps you can take. First, check if your vehicle has an automatic light switch or a manual one. If it’s the former, then the process of turning off the light should be easy: simply close the driver's door and wait for all other doors to get shut before starting the engine. This will turn off all interior lights automatically. Alternatively, if your car has a manual switch for this purpose then simply flip it off once you have closed all doors in order to prevent any unnecessary illumination coming from inside your car while driving. To make sure that no further undesired lighting happens during driving time (and thus avoid draining power unnecessarily), also remember to double-check that none of the cabin lights are left on after closing each door – especially at night! Ultimately, with some basic knowledge and common sense it should not be difficult to ensure that no more than necessary amount of electricity is wasted due to leaving interior lights turned on when driving around town; doing so could even help keep fuel costs down - so always remember these few easy tips!