Once you get the ability to start storing cars in the garage, go and jack 6 cars and you will unlock one of the race cars. This thing handles like a dream and has a super top speed. Then it just becomes a matter of outrunning them.
there's a perk where you can, also if you can manage to take down a nazi and change into his clothes while you arent being looked at you can skulk off to a hiding spot since the alert is temporarily deactivated.
I found out how to unlock cars ;P 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.
You should try to get all the perks 1st, because 1 of the lvl 3 Gold perks lets you use all of your hideouts and brothels when a level 5 Alarm is on. Also, in the Belle's underground wine cellar, there is a gambling wheel, were if you 3 star icons you will get a very fast civilian car, it only takes 25 contraband to play and with the trainer it's easy to get 1000 contraband. Also you should before getting a Alarm 5, go to the Farm, and save the teleport spot there, which should be option 5 and then when you get a alarm 5 you can just press option 6 to teleport yourself to the farm and then jump into the well.