Well according to GigantorX, it's not designed to influence behaviour, but rather to replenish coffers. 
I will stand by my opinion because I think it's closest to fact.
Incremental taxes like the proposed gas tax is stupid, plain and simple. Why nickel and dime it for 5 years to reach the .40 cent mark? .8 cents a year for 5 years will do nothing to change anything, it's to small an amount spread over to long a time. People will not even notice it and that's a fact.
It gives the people time to adjust and continue to drive the way they always have and continue to purchase the types of cars they always have. The govt. then gets the same amount of miles driven but with .8 cents a year taxed out of the fuel purchases. It's brilliant really. If the tax was something with teeth, say $.75-1.00 in a single year, habits would change and we would see a drastic change in behavior concerning miles driven and types of cars purchased....but that isn't the point of this tax because if it had balls then revenue from the tax wouldn't be as much as intended because fuel purchases/use would be down drastically. Hence the .8 cents per year.
