Read the online book Lights Out for a somewhat realistic scenario.
Go ahead and do a search for it, it's free to read online.

People in the cities will be SOOL *Shit Out Of Luck* when it comes to bailing out. If they do not have a destination they are worse off.
The gridlocked freeways and highways will be either killing zones, deathtraps from heat, robbing/looting zones, you name it.

Go on foot or bicycle if you cannot take a country road somewhere.

Plan out your route of escape ahead of time, time it, add an hour or two for worse case scenarios such as robbing, looting, gridlock, etc.

Have a designation planned. Alternate routes for driving, biking, walking.

Note where water and food *not likely food*, have a way to purify the water you encounter.

Take note of what areas you will be traveling through, are they seedy or rough, crime ridden?

Take everything seriously and be prepared. Do your research.
It will only take a day or two for people to turn feral.