Question

why should i conserve fuel and how ?

Answer 1

We should conserve the fuel, because the fuels are getting depleted, and the chance for the fuel in the future will be less.
Then, the future generations will suffer, with the lack of fuel.
If we didn't conserve the fuels, then, there won't be any re-accomplishment.

So, it is important to conserve it, as it takes millions of years for it's formation. 
We can conserve by using battery vehicles, and limiting the usage of the vehicles.

Answer 2

Several reasons: it's a finite resource that we are running out of (as far as fossil fuels go, we've already used half of all the world's available oil); conservation of fuel puts less of a strain on the global environment on several levels; and, from a community perspective, it's the ethical thing to do considering the major issues we are facing regarding natural resources across the board.