Apparently the diesel V-8 available in the 2007 Range Rovers is so quiet and refined that the Land Rover engineers felt there was a serious risk of people forgetting and putting gasoline instead of diesel into the tank by mistake. In the UK in 2005 there were over 100,000 cased of people mis-fueling diesel vehicles with gasoline. Serious and expensive damage can be done by running gasoline through a diesel engine.
To overcome this issue, the Range Rover engineers have come up with the Gasoline Fuel Guard. Gasoline fuel nozzles are narrower than the diesel nozzles so a the diesel can't fit into a gas filler, but the opposite is not true. However the gasoline nozzle is also longer and penetrates deeper into the filer pipe. The Fuel Guard has a mechanical shutter that is activated when a gasoline filler is inserted and prevents filling. This could save people from a very pricy error.
[Source: Automotive Engineering International - print only]