I disagree that its not vegan. Crude oil itself does not intentionally exploit or harm living creatures – no aminals are currently bred, exploited or killed to make crude oil. The animals died millions of years ago and no intentional cruelty is perpetuated today by using crude oil derivatives. I do believe the use of fossil fuels needs to stop, but from an environmental point of view rather than seeing it as a vegan issue.
It’s probably vegan, but your question is valid because of environmental concerns. If you are concerned about animals and the environment, what you can do is what I do: use only public transport. I walk alot for exercise and I use buses, trains and ferries each day. I also choose to live in a small, energy-efficient apartment and not overspend. Cycling is also recommended.