which car is gasoline less expensive ?

I am trying to decide which car to buy, I am from Costa Rica and here the gasoline is VERY VERY expensive, so first, I have to think which is the cheapest car to maintain.

Here is the list of the cars that I can afford now, so I would like you to tell me, in general, which car has the less gasoline consumption, and also, you can tell me why would you buy that car ?

Kia Sportage 2006
Kia Sorento 2005
Hyundai Tucson 2006
Hyundai Santa Fe 2003
Toyota Rav4 2003
Nissan Xterra 2002
Honda CRV 2003

Thanks in advance.