It generally sucks to be late for meeting friends and family for Iftar. The one consolation is that after sunset the roadways clear up a ton making driving in Cairo a lot nicer than usual.
Remember all the fun you had as a kid driving bumper cars? Well, in Egypt (and in Cairo especially) driving on a daily basis is a bit like that. ;-) Fortunately the car shops are really great with repair work.
In Egypt, riding in a taxi can be a real adventure. Taxis drivers are the ears and eyes of the city and talking to them (usually they are quite gregarious and talkative) can reveal tons of stories and insight.