garyb1st
Well-known member
Mileage on the new motorhome pretty dismal. Was expecting maybe 8. We averaged 5.87 before taking into account generator usage. I think we hit most every grade between the Los Angeles area and Salem Oregon, both going up US 395 and returning between the Coast highway, 101 and I5. After the Eclipse, we drove to the Oregon coast where we spent a few cool nights. But because of smoke from a nasty fire threatening Brookings Or, we crossed over the mountains. More hills from Lincoln city to Roseburg, OR Then after 200+/- miles south on I5, we returned to the 101 to avoid the heat. That was a long 4 hour drive along CA 299 with high heat and 4 or 5 construction areas with follow me vehicles. (I wanted to shoot one guy. He varied his speed on a long uphill grade between 20 and 30. Thought I was going to lose the Allison. Winds on this 23 day trip were not bad. The heat was. Consequently for much of the trip we were running with both dash air and one or both roof AC units. Between dry camping and some very hot days, we ran the generator 78 hours. When calculating mileage based on generator use, the numbers increase. If 1/2 gal an hour, mileage bumps up to 6.5. If 3/4 gph, it's 6.87. If 1 gph it's 7.29.
Most interesting was the computer read on mileage. On one long run from a few miles past Bishop CA, to a few miles before Lake Crowley, approximately 10 miles with a steady grade of about 6%, the computer was reading 2.5 mpg consistently. If so, that's 4 gallons of fuel to go 10 miles. Based on the overall mileage, I'd say it was probably a pretty good indicator. For most of that climb, not towing, I managed 45 to 50 mph. The motorhome without toad weighs 20,500. With toad, almost 25,500. The engine was screaming and hovering around 4,000 rpms. The engine fan seemed to be doing it's job but the noise level with both the fan going and 2nd gear screaming was pretty severe. Not sure how to factor in the grades and while we do well on a gently sloping downhill grade, on the steep downhill grades, the grade brake holds us pretty good but the RPM's are in the mid 3,000 to low 4,000 range. That has to negatively impact mileage.
Most interesting was the computer read on mileage. On one long run from a few miles past Bishop CA, to a few miles before Lake Crowley, approximately 10 miles with a steady grade of about 6%, the computer was reading 2.5 mpg consistently. If so, that's 4 gallons of fuel to go 10 miles. Based on the overall mileage, I'd say it was probably a pretty good indicator. For most of that climb, not towing, I managed 45 to 50 mph. The motorhome without toad weighs 20,500. With toad, almost 25,500. The engine was screaming and hovering around 4,000 rpms. The engine fan seemed to be doing it's job but the noise level with both the fan going and 2nd gear screaming was pretty severe. Not sure how to factor in the grades and while we do well on a gently sloping downhill grade, on the steep downhill grades, the grade brake holds us pretty good but the RPM's are in the mid 3,000 to low 4,000 range. That has to negatively impact mileage.