An alternative approach for gas tax that I've never seen much discussion about involves a rebate. Basically, you add $5 a gallon in gas tax, then rebate everybody the average per-capita amount. So if the average usage is 500 gallons per year (for example), everybody gets a $2500 gas-tax rebate on April 15.

The idea is that if you drive less, you are essentially making money off this deal. You still get the $2500 rebate, but you haven't paid that much in over the year. OTOH, gas-guzzlers won't get rebated as much as they paid out, and are effectively penalized for driving a lot.

Other benefits: It's revenue-neutral by definition; and, when gas is costing $8/gallon at the pump, it's a constant reminder to everyone to drive less.