In my country there are several illegal car dealers ( not so illegal but it's not completely legal, becuz here we can rent a car when we turned to 18 as a driver licence),
There is a problem on it, becuz u have to give them an unlimited paycheck (you shouldn't write the price in the check, it's just for guaranty that you will bring back the car + your passport.
I'm pretty sure that there is always car rental company like this in everty country cuz i saw something like that in some other country but with other rules.
If you found one, do not trust them immediately, just ask other or google it.