Question for Jon W.

[gmcbuffalo]

Jon with your records on fuel usage have you noticed a drop in MPG with the new low sulfur fuel?
GregM

[Jon Wehrenberg]

Yes.

When we first got the bus all our MPG hovered near 8.

My practice is to set the Pro-Driver back to zero every 5000 miles. I then could see what the average MPG was just before I reset it and I had enough miles to eliminate a high or low reading caused by hills, headwinds, tailwinds, running the OTR, towing, not towing, etc.

My recollection was that I was always around 7.9. to 8.0. I am now seeing 7.65 (last 5000 miles)

I have recorded every gallon of fuel going through it and it would be possible for me to determine my annual MPG for the last 5 years. I have almost always run at 62 MPH, but I have gone from a Jeep Grand Cherokee, a Dodge Ram 1500 4WD, and a H2 Hummer.

[GDeen]

Interesting - I am averaging right at 6.25 mpg after nearly 4000 miles over the past couple of weeks. 6 people and gear, OTR running almost continuously and towing a GX470. I generally set the cruise b/w 65 and 69 depending on conditions. Sounds like I am running a little poorer on fuel economy than others.

[gmcbuffalo]

Thanks Jon.
GregM

[MangoMike]

Gordon,

Just got back from a 2500 mile trip with your same conditions and showed 6.25 also, so don't feel alone.

Jon gets his great mileage as he holds all the traffic back at 62.5mph and they literally push him down the road.


Mike

[Sid Tuls]

Gordon, Thats what I get on mine and I always tow my Tahoe.

[GDeen]

Thanks Mike and Sid - that feels better.

I have found the Pro Driver to be a useful tool between fillups, and so far it seems very accurate. I reset the leg function after fueling and then can follow mileage, ave speed, fuel used, etc.

The PD is especially helpful in avoiding the dreaded diesel douche. I just run the nozzle on high up to within about 10 gallons of the Pro Driver indicated fuel used. Trickle the rest in till it clicks off and no overflow yet. Always within a 1/2 gallon or so of what the PD says I have used.

[rfoster]

Don't feel bad, I thought my poor mileage was due to 70 mph. I ran almost 600 miles last trip at 65 to 66 mph and got 6.39 mpg with no tow.

Jon gets so good cause he has pedals to help. I think he has a hummer pushing him too.

[Sid Tuls]

Roger & Gordon: Just wondering what your water temp runs & trans temp. I run @203 water and trans @197 Thats running @ 65-70mph on the open road.

[Jon Wehrenberg]

Speed has a serious affect on mileage. The reason its impact may not appear significant is because there are other factors. I picked my speed of about 62 for several reasons. The primary one is that I can set the cruise and at that speed I am not overtaking a lot of vehicles so I never have to disengage it to slow down when coming upon slower vehicles. I am running at a speed equivalent to a slow truck so I don't feel I am a hazard. (Others may disagree)

But there are some other reasons beyond speed that have a measurable impact on mileage, such as headwinds or tailwinds. When we went to Pahrump last year we encountered headwinds the entire trip west. Despite not towing for the 4200 mile trip and limited use of the OTR due to temps we ended up at 7.3 MPG. Driving fast is like increasing the headwinds. The return home from Pahrump did not gain us much because the tailwinds were significantly less strong than the headwinds on the way out.

Any moutainous or hilly driving kills mileage. You never make up the loss of mileage going down the hills.

OTR has a minimal impact on mileage, but there is some penalty. Towing also affects the mileage, but less if running on the flat, and more if running in hills. These are anecdotal observations and I have no way of quantifying them.

As to the speeds I drive.......I can and have driven fast and feel equally comfortable doing 70 as I do 62 as long as I am willing to accept frequent lane changes for passing and more use of the cruise control on and off buttons. But stopping distances on our coaches suck, and the faster I go the greater the increase in my inability to stop and control the coach. The amount of energy created with the increase in speed is not a percentage, but an exponential increase so our coaches start becoming dangerous at some point. All it takes at higher speeds is a blowout or a car doing something unexpected and you have a recipe for disaster.

If I need to get somewhere fast, I'll take the plane or leave earlier.