If you are one of the non-believers when it comes to how much money better gas mileage can save you, it is probably because you simply have not done the math.  After all, at a rate of 1,200 miles of driving per month, you will save $80 per month by driving a vehicle that gets 20 mpg instead of 15 mpg, at gas prices of $4 per gallon.  Step it up to a 25 mpg car, and the difference becomes an astounding $128. Remember, you can increase your vehicle’s gas economy by performing regular maintenance, inflating the tires, and driving conservatively.  Even by taking your 12 mpg truck and getting three extra mpg out of it, you can save $80.