I have been following budget announcements since 50 years. During Nehru's time, all policies of the government were in line with socialism and greater care used to be taken not to affect the masses. But that time, in every budget, there used to be increased taxation in different items to meet the financial needs of the developmental and non-developmental expenses of the government. Public was not expecting any relief measures in taxation. Then, first time in 1973, when Mr. Y. B. Chahan was the Finance Minister, petrol prices were hiked from 75 paise per liter to Rs. 3 per liter. That was the biggest shock. I was working in the Head Office of the Tata group company at Bombay House in Mumbai and a large number of my seniors stopped using cars or started pool system to economise on petrol expenses. After sometime they got adjusted to the higher price and everything was normal. But the biggest change that resulted was that the goverment realised the advantage of increasing the petrol price which they kept doing just 2 to 4 weeks before the budget followed by budget full of reliefs. Though the reliefs annonced used to be minor, like reduction in excise duty on pressure cookers or life-saving medicines, it was making the public happy. Since then, this method of increasing petrol prices before the budget became a routine matter.
To answer your question, in 2008, petrol prices were controlled and the extra burden was being borne by the government. But now, Mr. Murli Deora was successful in convincing the government that it is better to free the petrol prices as the government can be spared of the extra burden. In fact, this idea was implemented during NDA rule by the then petroleum minister and has been revived.
My forecast is that the control on petrol price will return once the government dilutes its holding in oil companies and public holding increases. Thereafter, petrol price control will be reimposed with some subsidy from the government like in the case of fertilizer companies.
Eventually, the world will have to divert to other sources of power like nuclear, wind energy and solar energy to reduce dependence on the scarce oil resource.