Without a doubt, Colombo, Sri Lanka. Once upon a time I would have said Tidewater, Virginia drivers, snort laugh, till I visited Atlanta, but that was nothing till I went to Boston, the New York.
Certainly these had to be the worst drivers in the world, until I visited Jarkarta, Indonesia. Yes, terrible traffic, but worst drivers? Maybe not. Until I visited Istanbul, Turkey. My mind was made up, yes, this is it, the winners, the worst drivers in the world, until I came here.
I have to say that the streets here are very scary! Especially the buses. There are two kinds, colorful unmaintained private buses and red government Sri Lankan Transportation buses. It's not uncommon to see one of these buses traveling at dangerous speeds weaving in and out of traffic. Add the motorcycles and trishaws and it's a constant soup of wheels.
Now I know that there are some folks reading this shaking their heads saying, no, the worst drivers in the world are (Your city and country here), well do post a comment and lets hear about it!