Recently, I found myself doubling the speed limit and overtaking across solid center lines, even though I was not in a rush.

I was aware of impetuous behavior as a symptom of bipolar mania, but feel stable right now. I didn't have anything to which I attributed the reckless driving, but I convinced myself it had nothing to do with the disorder. Having read the following article, I'm not so sure. The thing I do know, and had already spent time on, is that I must reign in my driving habits. I don't want to hurt someone, and so far I have been lucky not to.

I'm open to suggestions as to how I train myself to slow down and follow the rules of the road.

This is the article I read which makes me believe it may be connected.
Bipolar and Controlling Impulsivity | bpHope - bp Magazine Community