Look on the map at lvl 5 alert and you will see 2 green hiding spots. The one I used is a farm (where you save the girl from nazis at the start of the game). You hide down the well.
With infinite health its simple enough to run across the map to the farm/well.
p.s. you get the mission from the guy that let you buy black market goods.
When You have garage everything what you need to do is steel car and park it in garage and... Congratulations you've unlocked that car! ;D
But there are some exceptions for Aurora etc.
[Edited by Bali-X, 12/4/2009 11:35:53 AM]