I sympathise with the idea when it is so obvious that so many people vote without any idea of what they're voting for, but not an IQ test - an IQ test only tests the ability to do IQ tests. The people who do the very best on IQ tests are the kind of nerds and geeks who form high IQ societies, which tend to be quite bizarre. So maybe a quiz on what their party's policies are would be better - I'm sure many would be surprised!
I'd rather go for something about it being taught better in school, plus, given what we've seen in the UK this week, an appreciation of how coalition politics can work and the practicalities of what has to be done if there is no overall winner in an election. BBC Question Time last night was a stunning display of ignorance by the two journalists present, with a lot of good arguments by the three politicians who actually have to work with the results of a hung Parliament. It does Lib Dem "supporters" no good at all to be in support of a party that wants proportional representation when they don't understand that the inevitable result is a hung Parliament every time, which means a coalition if you're going to have a stable government that lasts longer than next Wednesday.
As Churchill said, democracy is the worst system in the world... except for all the others.
I can't help thinking of Plato's "Republic" in this context. He proposed rule by hereditary philosopher-kings, trained from a young age to know the issues, what is best, and how to rule. Even then he had to hedge it round with all sorts of restrictions because as we all know, we're only human, "power corrupts, and absolute power corrupts absolutely".