I just bought honda city 2011... done only 466 km and have the same problem... it is not a problem but a 'characteristic' of the car... there are many ways to minimise the delay and dead effect identified by you...
- Put some Hi Octane Fuel
- Also improvise on your gear change...
Note that 11 km / l is still not accurate since the electronic meter reads the idle gear position while in motion as maximum mileage efficiency... so dont let that 11km / l mark decieve... its not accurate...
Enjoy your car! Dont worry about it! It is with almost everyone including me...