I have a 16 bighorn v6. I drove a 19 classic hemi 4wd for over a week over same roads and traffic here are my observations:
Hemi mpg 17-18 idle time makes a huge difference
V6 20-22 idle time makes huge difference
Hemi is noticeable more torque. Off the line hemi will take less effort to get 4 car lengths forward. The v6 isnt far behind to get same distance. V6 stays in power band more often. Hemi not so much unless you are constantly accelerating.
I notice myself braking and accelerating more in the hemi. I am more of a smooth driver, less braking conservation of momentum. If you are a light on the gas pedal you will notice the hemi shift more often vs the v6.
The hemi will engine brake more with zero input. With the v6 I can stay on the gas pedal approaching sweeping turns and smoothly accelerate out. With the hemi I would brake or engine brake and have to accelerate out and immediately let go of the gas pedal once up to speed sometimes the trans would shift thinking I'm trying to slow down.
Hard to explain, it just feels like I'm constantly accelerating and braking more over the same roads on my way to work. In my v6 I can modulate just the gas pedal to control acceleration, the trans shift points and maintain proper speed and momentum. I drive nice paved back roads with sweeping turns at intersections.
With that said the hemi is more fun. Is it 3-5 mpg deficit more fun? More maintenance, more parts when it comes to major maintenance. I bought my v6 as a long term purchase 10+ years. I paid 23k with 20k miles last year. Trade in value was 25k and dealer original asking price was 28k and was dropped to 26k before negotiation. I couldn't pass it up. Also it's much faster than my 05 Yukon denali with the 6.0 and 12 mpg.