Require petrol stations to display prices from the road

In New Zealand most petrol stations only display prices for 91 octane petrol and diesel. Very few advertise their prices for 95 and 98 octane or LPG. They used to do this but over the past few years they have taken these parts of their signs down (they say to de-clutter the signs). In reality they have removed them because they make much larger margins (they have said so themselves) on these fuels. (95 used to be only about 5c per litre more than 91, these days it is often 12c or more higher which is completely unjustified). People should be able to see the price from the street before turning off the road and seeing the price on the pump itself.

There should be a legal requirement to display the following (if sold): 91 Octane, 95 Octane, 97/98 Octane, Diesel, LPG, CNG (and in future a clause to cover electrical charging) to save New Zealanders from being ripped off.