DML FAQ : General : How can I improve my gas mileage?

How can I improve my gas mileage?

  1. Lower the truck - this reduces airflow underneath the truck and greatly improves aerodynamics and handling - IMHO, the best way to lower is with smaller tires, lowered spindles and shackles as this will maintain most of your payload and suspension travel - you can also add an air dam and body side moldings to reduce airflow under the truck; however you are increasing the frontal area of the truck, not good for aero, but better than nothing. Also, block any unnecessary holes in the front of the truck, such as foglight cutouts.
  2. Add a cap or, better, a tonneau cover - removing the tailgate or leaving it down will NOT get you better MPG. At least on my Dak, under a carefully-controlled experiment, tailgate UP got 0.4mpg better than tailgate DOWN - if you don't believe me, you can get more info here: http://cartalk.cars.com/Columns/CC/CC7237TXT.html
  3. If your truck's computer doesn't advance timing with higher-octane gasoline (via knock sensor), then run lower-octane as it lights off easier and you will have more complete combustion (assuming your engine doesn't suffer pre-ignition). If you run your engine and transmission both a half-quart to one-quart low, you can increase MPG but may damage said components if you run them hard - that is mostly a trick for winning MPG contests.
  4. Narrow tires with low rolling resistance (usu. low-profile) - disadvantage is giving up some traction on dry pavement (read: poorer handling and braking). You can also add skirts to your rear tires, but it may look silly (ala Honda Insight).
  5. Changing spark plugs won't get you better mileage, unless they are 1) due for a change, or 2) you widen the gap on the plugs to take advantage of an aftermarket ignition - even then, the mpg improvement may not be noticeable. You can also try indexing the plugs - that is, take a marker and mark on the plug tip (where the plug wire attaches) the side of the plug that has the electrode. You then install the plug with various washers (specially-made) until you can get the plug gap (opposite the electrode) aimed toward the intake valve (or injector) when tightened. This starts the explosion at the top of the cylinder and helps to push the piston down - again, it may be insignificant, but some drag racers swear by it.

Contributed by: "mrdancer"
Last updated: Fri Aug 17 07:55:52 2001