I may be wrong, but I've owned many Dodge vehicles and I don't recall any Dodge vehicles that have ever stated that they prefer 91+ octane. The displacement really isn't an issue, but more so the compression ratio.

 

2004 Dodge INTREPID ES
POWERTRAIN
Engine Code / Name EGJ
VIN -
Cylinders V6
Displacement 3.5
Bore x Stroke 3.62 x 3.19
Compression Ratio 9.5
Fuel Type G
Fuel Induction SFI
Valve Train SOHC
Valves Per Cylinder 4
Total Number Valves 24
Horsepower 234 @ 6000 RPM
Torque 241 @ 4400 RPM
Max Eng. Speed 6800 RPM
Transmission Automatic
Drivetrain Front Wheel Drive
EPA City 19 MPG
EPA Hwy 27 MPG

Lower compression lower octane needed.

Our 3.5L Compression Ratio is 10.3

 

The compression ratio on my 1997 Dodge Intrepid 3.5L was 10:1, VERY similar to the compression on the Max.

-R

 

Seems like fuel economy results are not consistent from owner to owner.

Getting high mileage on the highway requires discipline - it's awful tempting to use those 255 HP. I have been really trying by keeping the cruise control at 65 MPH, and leaving for work a little earlier for less traffic.

Also, I have been measuring MPG manually from fill-up to fill-up, and then taking the average of 5 or so fill-ups to create a total average - because there can be a variance in the amount of fuel in the tank with each fill up.

Average is generally the high 20s to low 30s per tank. I'm sure on a flat straight hiway it's close to 40 MPG for a short distance, but any hills take care of that quickly.

I always use premium 91 to 93 octane unless forced not to. Also,I stick with major fuel brands (any major brand). In some parts of the NYC metro area, there are "discount" stations with what is allegedly premium for the price of name-brand regular. No way I'm going to feed my VQ35 anything but the good stuff.

 

do you believe that ignition timing makes a difference in engine output?