The two best things you can do to increase mileage is to take as long as possible getting up to speed and driving SLOWER than the speed limit! Im not a big government kind of guy. With that said the national 55mph speed limit saved BILLIONS of gallons of fuel. If you want save fuel, drive 55mph.
2005 KJ CRD Sport
Suncoast, Transco, Inmotion, Provent, SEGR, CAT2, HID's, Samco hoses, louvers, V6 airbox, Fumoto, 2.5" cat back no muffler