Hyundai Getz Engine Problems
Hyundai Getz 2010: Excessive fuel use
You are right, it is far too high for that car. Going by Hyundai’s official figures you should be getting between 5.5 and 9.5L/100km depending on the mix of driving you’re doing. I would be making sure all is well with the engine and the electronics that control it, and check the exhaust to make sure it’s not blocked.
Hyundai Getz 2002: Jerky acceleration
It sounds like it is hesitating when you want to accelerate. It would worth checking the spark plugs and cleaning and resetting the gaps if needed, also clean the throttle body, and check for any vacuum leaks.
Hyundai Getz 2009: Incorrect fuel consumption
Carmakers don't make claims in km/litre terms, so I don't know who made the claim of 20 km/litre. The official claimed fuel consumptions for your car is 6.9 L/100 km, which makes it 14.5 km/litre if you convert it to your terms. The official figures come from a standard laboratory test that every carmaker does and they're meant to be purely for comparison purposes to allow you to compare car to car, model to model, they're not a real life measure of fuel consumption. You need to recheck your actual fuel consumption before you take it back to the dealer. That way you know what it really is, and you would have something meaningful you could discuss with them.
Hyundai Getz 2010: Coolant replacement recommendations?
We checked with Hyundai and their advice was to follow the service booklet as it is produced with specific recommendations for this market, whereas the owner's manual is a generic publication for many markets around the world. The shorter period is definitely the one to use.
Disconnecting the battery before charging
There's no real reason to disconnect your battery when recharging it as long as the ignition is off when you do it.
Hyundai Getz 2010: Poor fuel economy
Hyundai claims your car should do 9.4 L/100 km in urban driving conditions. That's what they get under standard test conditions, and while that doesn't necessarily translate to the real world it is a guide as to what you could expect. On that basis your car is using too much fuel, but not enough to cause too much alarm at this stage. It is still quite new and the fuel consumption should come down as the engine beds in with more miles. I would take Hyundai's advice and monitor it through to the 15,000 km service and if it is still too high have the dealer run a diagnostic check on it.