Istanbul is about 3000 years old and built on 7 (some very steep, think San Fransisco steep) hills. It was never designed (if designed is a word you can use at all here) for either tall buildings or vehicles.

Over the past 10 years something weird happened, people started buying cars, and some people would buy more than one but as most people live in apartments in Istanbul it appears as though there are more cars on the road than there are parking spaces in some areas (I know this is the case where my in-laws live near Nisantasi).

In my experience Istanbul drivers will mostly adhere to traffic lights, but not necessarily to things like zebra crossings and road markings. The worst drivers tend to come from the countryside as they don't necessarily know the road layout and drive as though they're in a village or open countryside.

I've been told quite a few times that the only reason the fatality rate from car crashes is not as high as it should be is because for most of Istanbul it's hard to drive faster than 50kmh for any period of time.

Of course, if you really want to see what 'driving by inshallah' is like, then you need to go to Saudi Arabia. When god determines whether or not you live or die, there's no point in driving properly.