I wouldn't buy a car without them now. I have purchased one car with on and another where I got the garage to fit them. If they save you one knock then it's worth it. Obviously they don't stop you needing to look first but they are useful for tight spaces though more importantly as I am constantly at football matches, school, tennis club and other places with lots of children around some of whom invariably walk behind cars when they are reversing - you can't always look out the front and the back at the same time!