HEMI question

**scott5** · 06-15-2008, 01:23 PM

I was talking to some people yesterday about purchasing a jeep with a hemi and they said that the hemi's in them during cruising shut off 4 cyls so it gets better gas mileage, is this true? Does this only come in the jeeps or other models like the ram? If this is true how does it even work, does it cut fuel off to those cyl at a certain speed or rpm or what?

thanks guys

**blizzard** · 06-15-2008, 02:14 PM

yeah, only at cruise when there's no power demand half the injectors shut off. but all come back online when you step on the gas. haven't driven one but hear you can't even tell the difference? other makes/models have it too...

**SUPERDUTY** · 06-15-2008, 02:48 PM

i heard you can't tell the difference either. But I also heard they don't help any with mpg's lol

**INSANELY CRAZY** · 06-15-2008, 03:05 PM

buddy of mine has a dodge truck with the hemi and he was telling me about this. he said he dont notice a difference at all. it's called hemi 8 & 4 series.

**madmaxin22** · 06-15-2008, 07:01 PM

its called MDS... its a marginal increase in MPG... Overrated to me, as the new hemi's with it only get maybe 2mpg better than the original hemi's on the hwy.... Hardly a gas sipper as they state in the commercials...

**393rag** · 06-15-2008, 07:50 PM

GM has been doing this for years

**03 OW SVT** · 06-15-2008, 08:01 PM

My 08 GMC has it.(See Sig)...Its called engine managament. I only get about 9.5 MPG but I pull a 5,000lb trailer around all day for my business. I'm sure it would get 15 to 20 on the highway if it wasn't. You can't tell when it goes from 4 to 8 cylinders or vice-versa. It has good power also 315 hps stock

**1994cobra** · 06-15-2008, 08:21 PM

My 06 durango has this and it more annoying then anything.It feels like an upshift at the wrong time.

**Martin0660** · 06-15-2008, 10:59 PM

I've driven a lot of the Chevy Impalas with the displacement on demand system as rental cars. It's kinda weird, you can tell when it's going in and out, sort of a strange feeling. The GM's have a system monitor that you can set to know what mode its in, I geuss the idea is to drive it so it keeps in the lower cylinder mode. i really dont car about milage on rentals, so I keep my foot in it ;)

Bob Myers

**Stangman** · 06-15-2008, 11:50 PM

I have a Hemi Quad 4 wheel drive without MDS and to outer banks and back got a little over 18MPG highway....and about 6mpg drivin on the beach....So you might get 20-21 mpg in the jeep...but i'm guessing.

**scott5** · 06-16-2008, 02:54 PM

The reason i asked is because these trucks are selling for very cheap, i have found a few 30k mile rams 02 and newwer for sale for about 13k and its hard to pass it up especially since i will be getting a bike to ride mostly and live only 2 miles from work. and hoping to get a quad or something...

Thanks for the imput guys