5.7 HEMI & 87 octane gas

[mystere485]

Dustybutt......you didnt read the rest of my post... i have gotten 30mpg in my 300c with 87 octane. I was quoting someone else who said there was no way.

[oldmac1]

I also got 29.8 on the interstate on cruise when I had my 06 Signature Series and running 89 octane with the 3.5l. Always got over 27 mpg on the interstates without cruise on a trip. When I went to the Hemi on the same roads driving the same way the best I got was 25.4 on cruise and 23.5 without cruise. So I believe that with 89 octane you can get great mileage with the v6 and very acceptable mileage with the Hemi. Both cars run great on 89 octane and no noticeable difference with 91 octane. I think I will stay with the 89 as it seems to work so well for me.

[ozboy]

just to add fuel to the fire, in australia fuel ranges from 91 RON to 98 RON. I run the 98 in everything i own...cars, lawn mower, even the 2 stroke blower-vac. It may well be my imagination, but the difference is noticable. even the missus reckons she can tell the difference in her car if she goes back to the cheap crap ( which is blended fuel ). by the way , we're paying $1.40 ish per litre even for the cheap stuff, up to about $1.60 per litre for premium.

[HKS]

On my 3000 mile trips, I use 89 or 87 whichever is cheapest. I already said 87 without 10% alcohol gets me better mileage. I get lousy Mpg in Nebraska (22Mpg) because of alcohol (at 75MPH). I get fantastic mileage in Colorado (27Mpg) when going east to west. I do not use cruise control because it downshifts when going downhill. I hate to burn up the energy it took to get up the hill in the brakes and engine when going down hill. All states west of Nebraska give me better gas mileage.

By the way, one of the benefits of having a Hemi is to allow higher comression without needing higher octane fuel. Look it up.

HKS

P.S. The new Hemi is actualy a cross between a Hemi and Wedge Head design.

Originally Posted by jeepgrady

How are you only saving .30 per tank when 89 costs .10 per gallon more?

I've used 87 in both my C and WK for several years now. Performance and mileage are equal to when I used 89.

[Zimmy]

I'm depressed, I'm not sure I averaged above 14.9 mpg in my 2008 300C SRT8 Design since I purchased in Oct07.
I drove from Tampa Bay to Atlanta and got around 18-22 on the highway.
With normal driving, I think it averages 12-13, the one time I almost hit 15 was being very careful watching the TAC meter.
Type of gas makes no difference either.
I wonder if I need to take it in for service.
There should be no way a full on SRT8 should be getting better gas mileage, right?

[chuckkent]

You are doing good for a SRT8.....

[bigsnake]

He wrote SRT DESIGN, there's quite a difference from the SRT8!

[HKS]

I blieve the SRT8 does not have the MDS gas saving feature.

Let me know if I am wrong.

HKS

Originally Posted by Zimmy

I'm depressed, I'm not sure I averaged above 14.9 mpg in my 2008 300C SRT8 Design since I purchased in Oct07.
I drove from Tampa Bay to Atlanta and got around 18-22 on the highway.
With normal driving, I think it averages 12-13, the one time I almost hit 15 was being very careful watching the TAC meter.
Type of gas makes no difference either.
I wonder if I need to take it in for service.
There should be no way a full on SRT8 should be getting better gas mileage, right?

[richonetex]

30 MPG!!!

Not in my 2005 5.7 Dodge Magnum with 46,000 miles on it with cold air ram induction.

The best I get is around 22 at 70 MPH, however I do get around 18 in town if I’m nice, but driving it to have fun is more like 15 or less.

On a few trips driving at night in the desert I have set the cruse at 100 MPH and have left it there for over a hour and averaged 20 MPG, but of course it was very cool at night and flat, and no hills, using 89 octane gas.

NOTE: Keeping your car clean and waxed with aircraft polish is worth 1-2 MPG.

NOTE: You will loose about 5% gas mileage per 10% alcohol in your gas!

[chuckkent]

I'm not sure what bigsnake is talking about. Only the 5.7L at present has MDS and its the only V8 that gets decent gas mileage. I'm not knocking the 6.1L because it is purchased for acceleration and speed!!!!!!