i have Belta 1.3, best millage i got was 18.25Km/L on long drive without AC. local average varies from 12Km/L-14Km/L with AC. oil filter and air filter is same as corolla. i had to replace front grill, original costs 6000, while Taiwani cost 2000. original bumper cost 17,000.
Drive wise its a great car, its kind of car you would want to keep for pleasure driving. 2007 model, full options (Climate control, satellite navigation, push start) , excellent condition(4.5 Grade) will costs around 13.50 unregistered. 40K around for registration.
Comparing it with Suzuki DLX is not an apple to apple comparison. DLX is fuel guzzler since engine is DOHC based. i will be surprised if it can do 12KM/L. most of owner i spoke to were complaining for eating fuel. its sporty yes but a small car to spend million plus.
if you want city drive, go for Belta if you like JDM or Honda City if you want pakistani.
Forget CNG as you will waste your time in queue every second days for 3 days and then you will forcefully switch to petrol because of load management.