As petrol increases in price, it will provide natural incentives for people to look at alternatives such as hybrid vehicles. You don’t need Governments to pass laws or subsidies to force people over. It will occur naturally.
As an example I saw this article on hybrid car costs today. I’ve spent 45 minutes doing further research on hybrid vehicles and then calculated some scenarios in a spreadsheet. Outcome is that next time I need to buy a car I will seriously consider buying a hybrid because the benefits will outweigh the costs.
The market doesn’t always work (usually due to a monopoly situation) but most of the time, left alone, it will.