Horrible mileage... A nightmare...!!!

Purchased Redigo T(O) .petrol model 2 months back. Driven 1600+ kms. Worst fuel economy. Beyond my imagination. They claim 25 km/l. In city it gives only 9-10 km/l. In highway it has given 16 km/l ,both the cases AC on. Actually Nissan has cheated customers claiming 25 km/l to take some initial marketshare . but this trick is short lived. There was brake issue also. From day 1 I noticed brake pedal is malfunctioning. Everyday twice/thrice pedal gets hard suddenly...brake is not being applied when in need. ..very dangerous. Accident can happen. I contacted Chandrani Nissan service center in Kolkata. They agreed that they experienced this same problem in other few cars also. However they reset the chip functioning ( as per their version ) and last one month after this rectification I did not face the problem. AC is strong. Interior exterior is good. Look is nicely crafted. Light steering in low speed city drive. However in highway it gets balanced and stable. Engine is very noisy. Especially during starting the engine. Hard notchy gear. Not good. Only one back light lits during reversing the car. Very cheap and bad idea. Basic necessity and basic quality should be maintained in low price range car also. But Nissan has cheated us. Horrible mileage has become a nightmare. Thinking of selling it . But only 2 months car...so will not be a profitable proposition. But fuel bill is touching the sky. Really confused. Don't buy this car to avoid tension.