of course GM would want a higher gas tax.
But the real problem with that is, people already are driving their "guzzlers" you're going to put a lot of the country's poorest in pain because they can't afford to buy a new car. And even if they could, it'd probably still take years to recoup the cost in gas savings from the minimum $13,000 sticker price of a new car.
A higher gas tax would also increase the cost of commodities as shipping costs would skyrocket overnight. Once again, putting the squeeze on the poor who have a larger percentage of their income going to food.
That is such a one-sided view, it's not even funny.
Basically the gas-tax would take the weight off of GM's shoulders when it comes to offering competitive and fun fuel efficient cars that people would want to buy. GM could keep pumping out Aveo-like cars that sucked but were cheap and people would buy them because that's all they could afford.