go for a deisel. the current shape sells for around 7. so you should be able to get an ok one for around 670. its a good car. fairly cheap parts. and def a step above the cultus. but keep in mind that the car has been used and since its pakistan and your asking for a bargain, its a risk. if you want a hastle free car that you want to keep for a few years to come, go for the cultus. Or if you want somthing that you can keep for a while and then sell off go for the corolla.
if i were you, id go for the corolla. eyes shut. that extra amount is worth it. since CNG and Deisel nearly cost the same, why compromise on performance and trunk space?