[Leadfoot]

I have a programmer and write my own tunes. Mine does not have a fancy display however. With computerized tuning you can get the best of both worlds, better fuel mileage and more power at the same time. For instance advancing ignition timing. Unless you have forced induction or a diesel, de-tuning really won't help. I have switched from 87 octane to 93 octane and advanced the ignition timing which really helped increase partial throttle power and overall fuel economy. Since I have more power at partial throttle positions, I need less throttle to get moving. The extra gas mileage from the 93 octane outweighs the cost plus as an added bonus you have more power. You can also tune other things which will help with gas mileage sch as lowering your idle rpm values and leaning out the open loop fuel mixture closer to Stoich. If you have an auto, a programmer can work wonders.