please note that there is a big difference in Passo and Cultus, if we only compare the CNG mileage with petrol then we will might miss the core difference of features and build quality of JDM compares to PKDM. Passo 2010 onward is CVT Automatic which you will find in CIVIC and NEW City and might Suzuki will introduce it in NEXT CENTURY. Passo Hana Plus has climate control AC which you will find only in Corolla Altis (not even in GLi and XLi) or in Civic. Passo has Hydraulic adjustable driving seat which i have not seen yet or don't remember if it is there in new civic. Passo comes along the retractable led indicator mirrors which again you will only find in expensive variants of Toyota and Honda even GLi has manual LED indicator versions. Every part of Passo has a sensor even if your silencer gives you problem it indicates and pin point to the right problem instead of dismantling the entire car. Passo Interior leg space is better then Cultus or even equals to any big size car it is spacious. Passo Mileage without AC is far better then CNG (in winters it gives 16km) because CNG Filling is not less then a hassle and wastage of time or we will have to reschedule our daily routine for easy filling. mostly JDMs has pre installed navigation system which is not available in cultus ever.
now if you realize that these features are not countable in such reasonable budget then it will be little insulting to this Piece of Best Designed and Build Passo.
you can also explore the option of 660cc jdm cars if you don't carry the much load in your car and drive alone mostly. 660cc car can give you better mileage withing city drive with less load inside if you drive it under 80km speed.
now choice is yours. Remember when you decide to buy any JDM hybrid or non hybrid please buy the car with less mileage weather you have to pay more for it or not and better if you take some expert along for detail checkup before finalizing the deal.
Kind Regards LoLs