When u suggest ppl kindly dont make ur personal bias intervene
City Gives pretty decent mileage on petrol, expect like 14-15 in city with proper gear ratios, so need for cng is minimal.
Corolla is more of a rugged vehicle, and takes whatever u throw at it, but sadly 2010 model is underpowered. Body is too heavy for a 1300cc engine.
If u Put CNG in it, then ull be sheerly disappointed.
My advice would be, go for any car u like amongst the two but NO cng.
If u want cng, go for previous rolla or city not the new ones.
@ 16 year old boy who posted that city is poor on highways.
I AM DAMN SURE U HAVENT DROVE One coz ur not legal to drive. City is way enough for an average persons speed requirement.