If fuel economy concerns you, you've got the wrong car. DOD is a terrible system on these cars and they're much smoother/healthier when its tuned out. You can't have your cake and eat it with this one.

 

In the world of cars/modding/building/engineering, most people state this:

Pick two:
- fuel economy
- performance
- reliability

And the reason more often then not, you can only get really high ratings on two of the three. As a result, like Chibi mentioned, the auto manufacturers are normally (not always) trying to strive for a happy medium of all three.

Perhaps a solution for you might be to purchase an HP Tuner so you can make adjustments when you want. You could build a tune that gets the best possible fuel economy for your daily use and then another tune for when you are out cruising and want to enjoy the power and the ride.
There was a company that for certain GM cars was selling custom PCMs that you could have two different tunes on and change the tune by the flip of a switch (granted you would have to shut the car off to flip the switch to the other tune).

You are certainly open to explore and experiment, but you may be a pioneer on this one. I don't think too many people with LS engines were concerned with MPG.

 

My point is that everything is a tradeoff. If it was as simple as lowering the activation point for DOD and there were no other consequences, don't you think they would've done that? It wouldve literally cost then nothing to do it, but yet they didn't. Maybe the tradeoff is something you can live with (an engine that shakes and stumbles at idle), or maybe it's not. I'm just not buying that such an easy change would have a notable impact on mileage with no downside.

I certainly do think they could've got more power out of the engine. Clearly they've done it on numerous other 5.3 applications. The limiting factor here is that they were already pushing the transmission. For its time, in that class of car, 300 hp was more than sufficient, so I don't think it was worth the risk to them to try and push it to 325, 350, etc when it would push the trans even closer to its limits.

 

A straight 6 is as smooth as the LS4. Sadly, they never put the Atlas in the Monte, because it was too big to go transverse. A V6 over 200 hp would shake itself out of its mounts without balance shafts.

Low rpm's are from high displacement and more detonations. My father's last car, a Nissan station wagon, had two spark plugs per cylinder. The only time it was ever audible (and it was of course an I4) is when he refused to downshift while cornering.

 

You're at least the third person to say DoD is a terrible system on here, and the third to refuse to say why. Why is the engine healthier without it? (If it gets any smoother, it will have turned itself into an Atlas.)

 

I actually explained in my post why DOD is bad if you felt like reading and not defending so much.
I was going through 2 quarts of oil between 5000 mile oil changes. That's a significant amount of oil! I don't know about you but if my engine is blowing oil and black smoke out the tailpipes every time it changes back to 8 cyl mode, that's probably not very healthy. Tuned it out and no more problems. It's a great idea, but horrible design flaws.

 

Not only does DoD usually throw oil passed the rings when it turns on and off for most people, but when you do exhaust work on the car to make your exhaust louder, and DoD kicks in, your car will sound like a helicopter.

It's very loud, very annoying, and tuning it out was super quick.

 

Oil consumption is the biggest reason why it's bad. I've followed cars with it and a plume of smoke would come out when you step on it. The helicopter noise with aftermarket exhaust is terrible and the engine just operates smoother when staying in 8 all the time.