Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

I am not someone who says all peds / cyclists should wear bright clothes in the dark, but as a driver I know that when it is dark (and especially when it is dark and wet) it is very VERY easy not to see people (including cyclists with lights) until very late, .

So knowing this I assume you drive really slowly to compensate for your lack of ability to see people (It's called risk compensation)