All motor vehicles should have a test switch for all external lights. May be some do, but considering its a requirement to get your drivers licence there should be a feature like this on all vehicles sold new. As its impossible to check your brake lights with out help or a old stick.
Search Ideas and Surveys
It would be great if fridges with water Dispensers had a feature you could press 100mls or 200mls or any desired amount of water so you can just sit the cup under the delivery port press desired amount and keep doing what you where doing.