The Hyundai i10 and the i20 are both hatch back cars but differ in size, while the i10 is smaller it has its own virtues and is available in a 1.1 IRDE Petrol and also a peppy 1.2 litre Kappa Petrol engine while the i20 is a much larger and spacious car and falls in the large hatch segment. The i20 is also available in an 1.4 CRDI Diesel engine and the 1.2 Kappa Petrol engine which is same as the i10. There is also a 4 speed automatic1.4 Petrol version if you want an automatic transmission car.
The prices for both the cars are also different while the i10 prices start at Rs. 3.44lakhs Ex Showroom Delhi for the Base 1.1 IRDE version and Rs 406914 Ex Showroom Delhi for the base 1.2 Kappa engine car.
The i20 prices start at Rs. 4.52 lakhs Ex Showroom Delhi for the Base 1.2 Kappa Era varient while the Base Diesel i20 Era is priced at Rs. 5.73 lakhs Ex Showroom Delhi.
For more detailed about i10 and i20 please click given link.
Initially, Hyundai Elite i20 Magna comes with a petrol and diesel engine but a CNG kit can be fitted with the one which has petrol engine. You will have to sacrifice with power to get more fuel economy and if you convert a petrol car into a CNG car, you may loose the warranty on the car and resale value of CNG cars is lesser than petrol cars. It is always recommended to get the CNG kit fitted from the authorized service center so that you can avail the warranty services as well. Moreover, the performance will depend on how the car is driven and maintained.
Click here to find the nearest Hyundai service centre by selecting your city in the drop down list.
How much fuel goes into a car varies on a lot of factors. Now you haven't mentioned how many km did you drive post the low fuel warning light as that could also determine how much fuel goes into the car. Even though the manual says that the tank capacity is 45 litres, the amount can vary by a small margin, give or take 2 or 3 litres. Also filling fuel in the hot day or in the night also makes a difference considering fuel expands during the hot day and contracts when the temperature is cooler. All said and done, make sure you fuel up within 3 to 4 km after the low fuel indicator light pops up.