i also want to buy a JDM 660 cc, Mira,Alto excluded. i like Honda zest.but it is still rare and i am worried about parts(availability and cost).These days Ek wagon is selling more.it has slightly less features than zest but zest weights 910 Kgs and Ek 700 Kg,so thats a 200 Kg difference. i think thats why Ek is famous for its economy. Ek has 3 gears and zest has 4 gears,does it matter in economy ?
i have seen 2007 Zest in 8 lacks-825. and Ek is cheaper.2007 model is near 7lac 30-7lac 80 I will highly appreciate a quick advice 
other thing i have searched is that 2WD are better in economy that 4Wd versions,so my advice to others kindly take this into account when buying these 660 cc cars
Here is detailed info about Zest 2 ,3
Ek