I like your shifting to Nepal to save some sum through petrol. Why not you shift your residence to an oil producing country to save more money through petrol. Is the petrol and the vehicle only life on earth? Have you ever analysed the cost of other things in Nepal? Even in our local market, one shop keeper may sell onion for Rs. 20 per Kg, while the other shop keeper might sell it for Rs. 25. In Tamilnadu, the mutton is Rs. 700 per kg, where as in Bangalore the mutton rate is Rs. 500/- per Kg. This is between the states within India. Now the petrol rate is between two countries.
No life without Sun
As expressed by Sun within India the prices vary and as of now, I feel Hyderabad is cheap when compared to other big cities as far as the living index is considered. So don't worry about that. The amount you have to spend to shift your family will be very much higher than whatever you are spending on Petrol. Try to think of ways to reduce your petrol consumption.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease