Hahah, relax brother.
I have a couple of 660's too, one XLI and Civic.
Firstly, Mira has an awesome pickup, acceleration and fuel average.
My Mira gives 15kmpl in Khi with AC, and 20kmpl on highways with AC.
There is no heating issue whatsoever, I have driven the car on highway at 51c from Khi to Larkana that's like 500 kms, and guess what, the car performed better than many XLI taxis as Mira had better brakes.
Plus these dinkies have better horse power.
I am talking about the category of cars in .7 - 1 million, the best choice is obviously the 660's. Local third class, Cultus, alto and Mehran se to behter hain. Swift is 1.2-1.3 million, wagonR is also expensive. Baaki cars are mostly useless because they are really old. even if you buy XLI or GLI 2008, it costs 1.1-1.2 million.