This is a good spreadsheet, but I have a few questions. I hope this is the right place to ask, if not, mods please move my reply as you see fit.
1. Petrol prices are deregulated. Which means they will move (more or less) in tune with global crude prices. So what are your views on the same? Would petrol cost Rs 80/Ltr or would it remain fairly constant. For that I think we need to look at the trending of global crude prices for past few decades vis-a-vis taxation and processing costs here in India.
2. Diesel prices are regulated (discounted). How much would they be if they are deregulated? And then how would the equation be?
3. In 2009 when I bought my diesel hatch, diesel was Rs. 35-37 per liter. And now it is Rs. 42/Ltr. Still it's a good bet for me because the petrol prices rose from then Rs. 55 to Rs 63.
4. If the ownership is going to be more than 5years, what are your views on the same?
5. Maintenance costs for diesel have come down drastically. On the other hand, spares and labour costs will keep rising.
There are many more factors. Just trying to get the best view out.