Now, that car you drove, did it have a little picture of a glass bulb-and-tube thermometer on the dashboard, possibly next to a little warning light or on the dial of a gauge? Now, when have you *ever* used a thermometer to measure the coolant temperature in a car? Assuming you're not doing some extremely specific tests on the cooling system.
It gets worse, though. My car has no fewer than three little thermometer warning lights. One has a wavy line across it to show it's for water temperature (because it looks like waves on the sea, which is water, presumably). One has a little drop beside it - what the hell is that? Oh, it's oil temperature, and it blinks if you give it the berries when the oil is cold and comes on steady if the oil gets too hot. The final one has a pair of gears beside it. Gearbox temperature? No, hydraulic oil temperature, with the gears symbolising a gear pump - odd, since it actually uses a swashplate pump but I guess that's harder to do in a little white icon on a red lamp cover.
The one thing they have in common is that if they light up, another red warning lamp twice the size with the word "STOP" written on it comes up as well.
I think the worst example of an icon I saw on a piece of software was some radio GPS locator stuff. When it was trying to connect to the radio it showed a little animated icon of a plug going into a socket, over and over - cheesy, but I guess it makes the point.
What totally baffled me about it was this - if it couldn't connect to the radio the icon changed to a guy with a black-and-white striped shirt waving his arms. Now, since the software was pretty crap this happened quite a lot. "Aw, no, it's gone stripey-shirt-guy" was the frequent complaint.
It was only months later that I mentioned this to someone at the company that produced the software, a company somewhere in the US. "Oh, that means it's timed out", the guy said.
"Really? How do you figure that?"
"Ah well it's a baseball umpire signalling time out, you see, having the icons saves having to translate all the error messages"
Yeah, maybe it works in the US, but in the rest of the world where no-one plays baseball it falls over pretty badly.