Zombies are everywhere and there will be more if you can't go out of the city. More populations means more zombies as their numbers grow for every person that they killed turns into one of them. The only way to kill them is by destroying their brains and that is hard for most people. If you want to live longer then you should escape the city. Fortunately, you got a car that you can use to escape. You don't want to turn into one of them. Your best bet is to get out and get to the safe zone, where a number of survivors are holding their own against the undead.
The car will run as long as there is still fuel left. You need to activate the booster to travel faster. You can activate the booster by doing some flips up in the on the air. Grab some coins as you can because you can use it to buy some upgrades.