Best MPG?

[KeithStone76]

That's possible; it's also possible that it's just too soft for you to pick up in your very quiet limited interior or that your hearing is no longer as good as it used to be ?

Here's the thing; these engines are built to extremely tight and close tolerances. They're all running the same software/computer. So given the same gas and conditions, there's a 99% guarantee that your hemi will react the same way as mine will. And if I can hear pinging, that means yours would also be pinging.

Given that Ram recommends 89 octane, and there are videos on youtube where they actually record the computer still having issues with 89 octane (but less so than 87), running 87 may as well be running ditch water at that point.

I'm running 91 now and it's like it was finally set free from ****ty gas. It just runs so much more effortlessly. I didn't notice it right away. Took like about 3 tanks before it occurred to me that wow, this thing is running really really well now.

There is one little thing though; the pump I use has up to 15% ethanol in regular, and 0% ethanol in 91. So maybe the ethanol is also playing a part?

Ethanol is the devil!

Sent from my moto e5 play using Tapatalk

 

[paxton306]

I took 150 mile highway trip taking it very easy and was able to get 30.5. This was on flat roads and in eco mode almost the entire trip.

 

[paxton306]

 

[paxton306]

Guess it was 30.2

 

[JimD007]

If your engine pings, I agree you should put in higher octane. Detonation can significantly damage an engine although with modern controls it will probably not get that bad. But it doesn't help anything and the engine will not be efficient running that way.

You can also gain enough on mileage to pay for the more expensive gas but that is not the case in my other vehicle, a BMW convertible. BMW recommends 89 octane for it and I gave it that for several years but decided to try 87. I've run over 30K miles on 87 after running even longer on 91 or better. Mileage on 87 is slightly better. That makes sense because the higher heating value - the energy in the gas - is actually higher at lower octane. It also does not ping including when I towed a little trailer with it.

I used to have a Suzuki SUV with a little V6. 87 was recommended but it pinged in hot weather and especially when towing with 87 octane. Reducing the spark plug gap to the minimum helped. But I would just put in 91 or better when I towed. My son owns it now, he hasn't mentioned any issue. It's up around 200K miles now so compression may be down a little.

 

[JimD007]

I just got back from a trip of a little over 1,000 miles each way. I cruised 72-73 going out and 75+ coming back. I got 24.7 and 25.9 on two tanks going out and 21.7 and 22.6 mpg on the way back. Seems like speed is a big factor. I got as much as 591 miles on a single tank. My cumulative mpg is now just over 22 mpg (over 5204 miles). All these are from my spreadsheet, not the truck. I've seen it claim over 28 mpg. My truck is 2WD and has a soft tonneau cover. It didn't help my mileage but I got the speed up a little a couple times to get around traffic issues and the V6 sounded really good up around 4-5,000 rpm. I never felt underpowered

 

[Lil'Mike]

I’m hoping the my Pentastar will continue to improve MPG numbers, as I’m getting 17 average when primarily city and 19 average highway. Currently at 2500 miles. There doesn’t seem to be many performance options as the 5.7 to try and better MPGs. I have a K&N drop in and Corsa catback work in process, but that’s another thread.