I have an 07 hemi with MDS and i wanted to let everyone know that i usualy 87 gas, and i was averaging 14.6 mpg, at 65-70 mph, i put 93 rating in it and i was averging 19.4-19.6 mpgat 65 mph has anyone else seen this?, does anyone know why there is that big of a differance?

 

HAHA. Not saying you won't get increased gas milage, but not that much.

One thing you will want to note. If you have a FULL tank of gas, reset your overhead and drive on the highway you will get a higher MPG than if you reset with 1/2 or less of a tank.

Also note, that is a overall average. There was a guy in a SRT forum that thought it was more of a instant thing, he said he was only getting 9.8 on the highway, but of course he had 1000s of miles on that 9.8, he reset while on the highway and was getting 15.

WIth that said you should get about 19. But your 14.6 is wrong for highway. Had a low tank or had a bunch of city driving mixed in there. I know my Hemi 4x4 without MDS gets 14 on average and I have seen 18+ on the highway if I reset while on the highway. Oh and I run the recommended 89.

 

I reset it all the time, it keeps me in check with how much i put the hammer down, I just thought it was strange when i put the 93 in that it would be that much of a differance, I did notice that it would stay on the mds for longer periods of time, it used to come in and out of it alot, the only thing i can think of is that the 93 makes more efficiant power on mds than the 87 does, what do you think

 

I could be wrong but i think its recomended higher octane for hemi engines . I noticed the engine runs smoother as well
little diffrence in mph. (94rt10ohio) you run 89 octane in the hemi?? or the Vipers??

 

i suggest you read your owners manual, i have the 06 ram hemi and it recommends 89 octane. it says that you should not run a higher octane gas then what is recommended for your truck. i think your just paying more at the pump!!

 

Thats what i mean it says to run premium not 87 octane and i thought 89 is mid-grade and 91 is premium ,am i wasting my money??? should i go with 89??

 

yes thats what dodge recommends to run in your truck. start getting 89 octane and save a few bucks at the pump. your truck doesnt need higher octane, it was built to run on 89 octane.

 

Thanks im going to start , our gas here in Ontario is gone crazy , average is 1.05 pr litter , high octane well over 1.10per litter. 89 it is.

 

89 in the Hemi, the Vipers get 91 and higher. And as others and myselfstated, 89 is what the Hemi recommendation is from DC.