Improving performance, Mileage, efficiency

What ways would you suggest to improve performance, efficiency, mileage etc on a 2004 GMC YukonXL? Things like exhaust,Spark etc.

same for any vehicle…keep maintenance up to date, tires inflated properly, no jack rabbit starts, keep highway speed about 65, …I am sure there will be more suggestions…

Get a good quality dial air pressure gauge and set the tire pressure at the recommended settings in the owners manual. If you want you can even add 2psi to what they recommend. Other than fresh spark plugs and making sure your oxygen sensors are in good shape there’s not much you can do mechanically to the car. Any small gain you might achieve by optimizing the computer by chip or opening the exhaust would be offset by the cost of these products.

The only other thing I can think of is when it comes time to change your tires opt for a model with low rolling resistance as this can improve mileage a bit. Oh, and as the previous poster mentioned travel at 65mph or slower, as the wind resistance at 70-75mph consumes significantly more fuel.

Really there is nothing special. Basic maintenance and conservative driving will do more than all the gadgets and other tricks combined. Remember next time buy a car that fits what you want. Changing them later is seldom the best idea. You certainly don’t have the car for getting good mileage.

Life is about trade off’s.