The ILO option comes free on all British cars (by order of the Queen). Sort of a passive warning system for fluids, if you don't see the offending fluid then it's empty. More accessible than a dip stick. And not pricey like the Rover Cars "Ice Alert" system, to warn of approaching glaciers (after the Titanic, an option by Royal decree)... [This last one's real, there was an "Ice Alert" option, I have one from my '70 Rover 3500S.]