Re: Wanted to start a fuel petrol saver business
If you have no URL so far I expect you do not have Adwords account either. But if you do, you can try Keywords planner. You can find this helper in tab ''Tools'' in top horizontal menu. You can add keywords/field that you are intested in and it will show you competition on these keywords, avg. monthly searches + suggested bid.
In case you really do not have adwords account you can use this: Global market finder, which does almost the same thing.