It's a terrible idea...

to impair motorists' ability to control their cars in the name of safety. In some circumstances, you need all the speed you can get to avoid a catastrophe, and making it difficult to summon whatever power your car has is not smart. Besides the fact that I don't like this whole class of ideas, this one has fundamental conceptual flaws. What does "significantly exceed the speed limit" mean? Many cars have top speed governors anyway, but they are set so high as to not impose on normal driving (at least here in the U.S.). It seems to me any system like the one proposed that is set to intervene at a speed where it will make a difference will also cause safety problems. The alternative given in the article, a speed warning system linked with GPS, is fine with me; sometimes I just don't realize the speed at which I'm traveling. But that gives the choice, and full control, to the driver. And that's a good thing. Now, if we would just train our U.S. drivers properly...