If traffic doesn't allow you to coast or cruise, your fuel economy will not be good.

It's not so much the rpm as the momentum. Every time you come to a complete stop or lose a lot of speed, you will nee to use extra gas to get back up to speed. If you want good city economy, either plan your trips so you won't see traffic or stoplights, or adjust your speed so that you just get to the stoplight right before it turns green. Keep distance to the car in front of you so that when he brakes, you don't have to... you can just let off the gas pedal and slow down to his speed.

7 km/l is either terrible or normal, depending on how long your trips are. But I've seen as low as 4-5 km/l from 1.4 - 1.8 liter cars in Manila traffic over the summer due to the terrible traffic caused by construction... what you get in summer traffic or cold Christmas traffic will not often match what you can get during regular driving months.