Hi Vinay, Thanks for your question, Honda City fuel tank capacity is 42 liters and there is a vacuum space in overflow tank ranges from 2liters to 3liters. But it is not safe to fill the vacuum space. Thank You
Certainly, you can get your car modified as per your choice. Coming to the front grill, you can replace it with the different grill. For that, we suggest you to get in touch with the authorized service centre as they will be the best people to suggest you few compatible grills to choose from.
Click here to find the Honda service stations by selceting your city in the drop down list.