Is there an 'optimal' RPM for mileage?

CRD Joe · **Posted:** Thu Mar 03, 2011 8:36 pm

I got over 38 MPG on my 2600 mile drive home from Nashville to Seattle driving just below 60 mph in the 1700 rpm range.

RJM · **Posted:** Fri Mar 04, 2011 7:40 am

You must have been going downhill with a strong tailwind all the way.

LibertyCRD · **Posted:** Fri Mar 04, 2011 8:39 am

RJM wrote:

You must have been going downhill with a strong tailwind all the way.

.......with the transmission in neutral and the engine shut off.

bhc04 · **Posted:** Fri Mar 04, 2011 10:28 am

Now you guys and gals may not believe this but it is honestly true. Back many years ago I had a 79 V.W. Rabbit diesel, 5 speed. Driving from San Jose CA. to Palm Springs for a long weekend and a "tail wind" of I'd say probably 30-35 mph, I got 72 mpg on that drive. Those who may not remember the old Rabbit was very light and had a square back end that was perfect for acting like a sail.

Roostre · **Joined:** Sun Oct 24, 2010 3:57 pm **Posts:** 195

So I filled up last Friday (Feb 25) and did everything I could to keep my rpms down. There are a few sections of highway that I have to do 65 or I will get killed/rundown, but most of the way I tried to keep just under 60 mph (about 1600rpm).

Well i am most happy to report back one week later that my trip meter is at 175 miles, and my fuel gauge is still above 3/4's of a tank. I estimate this to be ~6 gallons used. This means I have gotten over 29 mpg this week! And this is with a bad thermostat holding me back!! :BANANA:

My commute is 80% highway and 15% city stop and go. The EVIC is as high as I have ever gotten commuting at 30.3 mpg.

nursecosmo · **Posted:** Sat Mar 05, 2011 10:23 am

I have gotten as much as 36MPG on the freeway but it was very painful. It involved driving in 5th gear, locked up at 56MPH. Most of the gain comes from other cars and trucks passing me and pushing the Jeep with their air displacement. I can only get that kind of mileage on a freeway with fast, heavy traffic. When I drive the same speed on lightly traveled country roads, I can only get 28-30MPG.

On the few occasions which I've driven trips at speeds >80MPH I have gotten 29-30MPG. These trips involved a lot of heavy acceleration around slower vehicles and up hills etc. I don't have an explanation for this other than that the engine must have been running hotter and the ECU must have advanced the timing more or something because it goes against all contemporary wisdom about efficiency.

SLS · **Posted:** Sat Mar 05, 2011 12:08 pm

I agree with papaindigo & GDE, there are a lot of variables!
Even drive train oil can make a difference. But the one that seems to really kill my mpg is the winter blend fuel. My CRD loves 70 MPH in the summer. On an average interstate and good fuel (I like B40 or B50) even straight dino I can average 34 mpg at 70 MPH. Just can't get it in the winter in upstate NY. On a trip from NY to TX we got 37 mpg once. We even stopped at Willie's Place at Carl's Corner, TX for some biodiesel.
http://www.youtube.com/watch?v=f_dyhCY9At0

RJM · **Posted:** Sat Mar 05, 2011 7:36 pm

Do I hear 40mpg? anyone?

SLS · **Posted:** Wed Mar 09, 2011 2:36 am

Maybe with a GDE tune we could................
If the fuel prices keep climbing we may be walking or riding a bike

Joe Romas · **Posted:** Thu Mar 10, 2011 10:15 am

SLS wrote:

I agree with papaindigo & GDE, there are a lot of variables!
But the one that seems to really kill my mpg is the winter blend fuel.

Actually some one recently pointed out that winter fuel is only a small part of it based on the btu content and percentage of kerosene used :jester:

I think a better answer is WINTER in general :JEEPIN:

Roostre · **Joined:** Sun Oct 24, 2010 3:57 pm **Posts:** 195

CRD Joe wrote:

I got over 38 MPG on my 2600 mile drive home from Nashville to Seattle driving just below 60 mph in the 1700 rpm range.

Anybody that can stay just under 60 for 2600 miles DESERVES to get 38 mpg+!!!

I couldn't do it. :seuss:

Joe Romas · **Posted:** Fri Mar 11, 2011 7:46 am

Roostre wrote:

CRD Joe wrote:

I got over 38 MPG on my 2600 mile drive home from Nashville to Seattle driving just below 60 mph in the 1700 rpm range.

Anybody that can stay just under 60 for 2600 miles DESERVES to get 38 mpg+!!!

I couldn't do it. :seuss:

I hope he had a "slow moving" orange triangle on the back :jester:

WolverineFW · **Posted:** Fri Mar 11, 2011 1:05 pm

Joe Romas wrote:

Roostre wrote:

CRD Joe wrote:

I got over 38 MPG on my 2600 mile drive home from Nashville to Seattle driving just below 60 mph in the 1700 rpm range.

Anybody that can stay just under 60 for 2600 miles DESERVES to get 38 mpg+!!!

I couldn't do it. :seuss:

I hope he had a "slow moving" orange triangle on the back :jester:

Nope...that was on the farm tractor acting as his escort. :jester:

Is there an 'optimal' RPM for mileage?

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