I placed a post that was too general as I was in a hurry. My error. Let me clarify.
The replacement for displacement is increased efficiency. Sounds stupid? Well, the competitors don’t think so and prove it all the time.

I am not happy that a 5.3 V8 is being sold with those hp/tq numbers. I am basing this lack of efficiency solely on hp/liter ratio. Not completely scientific as there are other factors like low-RPM hp vs. high RPM hp. However, it’s sad when all we can do is make an engine bigger to get some numbers where the competition keeps the current size and increase MPG and HP.

Examples of hp/liter ratios:
Grand Prix V-8 5.3L 303HP: 57
Mustang V-8 4.6L: 300HP: 65
300c V-8 5.7L 345HP: 60

Grand Prix 3.8L 200HP: 52
Montana 3.4L 185HP: 54
Taurus 3.0L 153HP: 51

Accord V-6 3.0L 240HP: 80
Frontier V-6 4.0L 265HP: 66
Altima V-6 3.5L 245HP: 70

Cavalier I-4 2.2L 140HP: 63
Civic I-4 2.0L 160HP: 80
Altima I-4 2.5L 175HP: 70


I see we are getting better at it with the new models. The Lacrosse and the ford 500 are examples of some progress in the art of more power with less liters.
Buick Lacrosse 3.6L 240HP: 67
Ford five hundred 3.0L 203HP: 67

The “No replacement for displacement” ideology was good in the muscle car era but holds a lot less water when designing engines for the 21st century.