Just think of those electronic signs near school zones that flash up your speed and warn you to slow down. They are remarkably effective.
I got to thinking about this after test driving a Honda Insight. It's a petrol-electric hybrid car that has all sorts of techniques to reduce fuel consumption.
I found its best trick is the green light that shows up on the dashboard whenever you are driving carefully. When you put your foot down it changes from green to blue and shows the fuel consumption at that moment in litres per 100km.
I found myself leaving my foot off the gas to hit the five litres per 100km target I wanted to achieve.
It got me wondering. Just imagine if New Zealand's politicians and consumers had a feedback loop applied to their spending and borrowing.