Hey daniyal bhai, don't be worried about others response. And like everyone else said, you've made the right decision buying a prius over a slower uglier 1.6 thief magnet. Race it with an Altis, and you'll win. Drive it along side an Altis and you'll get better mileage. And use the air condition it'll be more comfortable.
And if you're so tensed about mileage, try this before eid holidays: reset your trip meter (the one not being used) drive your car on ring road at 60km/h in the evening with the A/C off for atleast 30km. And by the time you get home you'll have a trip average in the high 30's over maybe 40kmpl even.
If there's since rattling noise in the dashboard, try to locate which side rattles, take the car to a good mechanic. Have some foaming done and tighten the screws nicely.