Whenever I mention a gas tax increase, a few people jump in and complain that it's bad because it's a regressive tax. It is regressive for people who drive, and I'm certainly for alleviating the burden on the poor in other ways to offset, but the fact is that the regressive nature of the tax is already offset by the fact that poor people are much less likely to own cars and drive.
Obviously this is largely a distinction between the rural poor and the urban poor, and I have no desire to impose additional burdens on the former, but when it comes to worrying about the potential problems facing "the poor," a modest gas tax increase is really not high up the list. If you desire to advocate to improve the plight of poor people, the fight against a gas increase really isn't the most important use of your time.
...to put it another way, if you want to argue that a gas tax increase should be partially or fully used to, say, increase the EITC or to support policies which improve transportation options for the poor, I'm with you.