Should our RV be getting only 7 mpg?
 

Hi all.

We have recently travel about 1000 miles cross country in an RV. Long story short is the gas mileage seems to be particulary bad on this trip. My SO swears back before my time on the scene the RV got something like 14 miles per gallon. And that was with towing a car, probably driving a bit faster, running the generator (and both the AC units that run off the generator) and smidge more stop and go traffic to boot.

THIS trip we are averaging more like 7.5 give or take. I've never bothered to keep track of our mileage on all the shorter (couple hundred miles tops) trips we do fairly frequently, so I don't know whether this a new thing, a gradual thing, or my SO's memory of the good ole' days is just wrong.

One thing is different. We are now towing a Jeep Liberty with 2 canoes on top rather than in the ole' days which was just a smaller more streamlined Saturn car without boats on top. But the Jeep and canoes still appear to me to be mostly in the "slipstream" behind the RV. I could see it increasing the drag a bit more than the old Saturn, but I can't imagine it dropping the gas mileage by 50 percent.

The RV is a 35 foot class A motorhome. Model year 1997. It has the older "basements" so I supect it is not quite as tall (and therefore draggier) than newer models. It has 37,000 miles on it. The engine is a Chevrolet 454 7.4 liter V8 Vortec engine with SFI (which I guess is some sort of fuel injection system).

We are typically driving it in the 60 to 65 mile an hour range. We left from the south and are now in the midwest so its not like we are climbing mountains either. Its mostly been interstate or good highways so not lots of stop and go traffic either. If I assume worst case fuel consumption for the generator running full out (according the manual), the mileage is more like 8.5 miles per gallon.

So, given all this, is this the kind of mileage one would expect?

One thought I've given is to try a fuel injector cleaner before we head back in a few weeks. Any recommendations as to brand/type and hints on using it? Or is using it a BAD idea? Even if it helped just a bit on mileage it would probably pay for itself on this trip alone.

Any hints on what else to possibly look at? I could probably do the air filter, spark plugs, and spark plug wires myself before heading back. Maybe the generator is REALLY sucking gas?

thanks for any hints or input!

7.5-8.5 miles per gallon sounds about right.

A lot of large SUVs will get down to 14 mpg on the highway, and your RV is a lot larger than those.

you're lucky to be getting 7.5, IMO.

http://www.rvmechanic.com/rv/motorho...read_full.html

Seems about right.

That 454 is a big engine! From what I understand 10 MPG is pretty much standard for the fuel-injected big blocks, but that's when they're in empty pickups! With all the however many tons of RV goodies (and that 2-ton Liberty), I would agree with the others that 7.5 MPG is quite good.

Al-co-hol
 

Your mileage sounds about right. I did not see the gross vehicle weight, but that engine is not great for mileage. You may indeed have gotten more mileage in past years before they increased the amount of alcohol mixed with the gas. Everybody's mileage went down. My pump says the maximum amount of alcohol is 10%. I bet it's even more than it supposed to be. I think a lot of us are using E85 without knowing it and paying for pure gas or at least E90.

E85 is 85% ethanol
The stuff you buy at the pump would be E10.

I doubt that someone would be selling E85 as E10, and in many cars they are not able to run E85 at least without setting off the check engine light.

Thanks folks.

Sounds like the SO's memory is faulty. And thinking about it, moving this much crap around and still getting mileage that "good" is surpising.

In conversations like this I always like to point out that Ms Hook and I get over 13 MPG when pulling our 12,000 lb 5th wheel.

On flat ground near sea level (I-5 in California) we generally run closer to 15 MPG.

7-8 mpg is really what you should expect from a 35ft AND tow at that speed. I have a 30ft '92 Fleetwood with the same engine, I'm not towing and get a little better mileage from an Allison transmission in overdrive (~12 mpg) under absolutely ideal conditions (no side wind, flat-ish road and 55mph.) Of course that's an extra day off my vacation but heck - what's the hurry?
Also when on the road my water tank is only 1/4 to 1/3 full. There's plenty of water where I'm going, no need to add weight and I sure as hell won't take a shower at the roadside turnout.

Oh and did I mention that I'm hypermiling whenever I have the chance.

You're running a gas generator at the same time? You should be able to calculate how much fuel it burns an hour and add that back into to your fuel economy calculations.

That's impressive. Is the tow vehicle a diesel? The OP's mileage sounds about right to me. We pull a 5th-wheel+boat combo that weighs a little less than your fiver. I've yet to get 7 mpg. Usually 6-6.5. I suspect that some of the difference is due to friction of having 12-wheels in the ground, and that our rig as a whole is very un-aerodynamic (gaps betweeen truck/trailer, and trailer/boat). We've just had to accustom ourselves to the fact that a long weekend at a faraway lake will usually run us around 120 gallons of gas, when truck, boat and generator are all fed. But having the place to ourselves is worth it.:)

On edit: The truck is a gasser.

Hi all.

Again guys thanks for the input. Sounds like things are just as they should be for us gas mileage wise. Oh, did you know they make sausage gravy dispensers? Like the ones you see at fast food places for fixing your own drink, but for gravy instead. This place had a dispenser that popped out a biscuit in a bowl. You then took that biscuit/bowl, peeled off the plastic covering, placed it under the gravy dispenser, pressed a button, and filled er up.

Wait until the Deep South hears about this modern marvel.

"hears about?" how in hell did the Deep South not invent this? It sounds like all kinds of awesome.

Yeah, personally I am a bit embarassed about that myself...We decided to take pictures and we were a bit afraid the folks in this middle of nowhere country "store" would take offense. But they were proud of it and even opened it up so we could see the magical inner workings. I told them I thought there would be like Kebler elves in there with a tiny stove tops and pots slaving away, but alas it just a kinda like a giant hospital IV bag except filled with sausage gravy. Some mysteries are better left unsolved I guess...

Anyhow, if you must know more, do an internet search for Bob Evans gravy dispenser. You can get one magical dispenser AND 4 cases of IV gravy for under $600. Apparently the Bob Evans company IS east of the Mississippi but I don't know how southern it is. I just know I've never seen one of those contraptions down south. Then again I don't get out much fast/junk/convience store food wise.

If I do win the lottery I will say I'll buy one of these babies before I buy an expresso machine.

Bob Evanses are quite common in Michigan, so 'taint all that southern.

First the civil war, now THIS. Oh, its on now baby!

Oh, I started a thread in cafe society about this if anyone is interesed.

Late to the party on this one, as we've spent the last week on the road in the John Day area of Oregon. Our old RV was a 27' Class 'C' with a Triton V-10. It got 8 mpg regardless of whether or not I was pulling a toad, uphill, downhill, etc. The marvels of metered fuel injection. My present RV is a Class B (van conversion), which gets about 12+ with a V-8, but that should improve over time, since I only have about 2,000 miles on it.

For me and my family, gravy is considered a beverage, so I'm all for a dispenser. In fact, I had thought about opening a gravy bar, much like an espresso stand, where I would dispense shots of one's favorite fat-based substance. I was going to call it "One Foot In The Gravy". Any potential investors may contact me via PM.

My in-laws had a huuuuuuuge RV which, when fully laden, was noted to be approaching the "gallons per mile" designation.

God, I love sausage gravy. If I had a motorhome, I'd have a sausage gravy dispenser in it.

Seems like your OP has been answered pretty well. And it's what I would have said too, 7.5 mpg for a 35-footer with a big block Chevy and towing is, as someone said, fairly decent. And I think your SO is mistaken about ever getting 15mpg. My 2004 Nissan Pathfinder SUV with a 3.5L V-6 (~215 cid) only gets about 15 city and maybe +20 highway (with a tailwind!) And that's not towing & with only my 180lb self in it!

Don't be too jealous of diesel pushers either. Yeah, diesels do get better mileage pulling heavy loads, but:

1. They cost a lot more up front to buy.
2. Diesel engines cost significantly more to be serviced or repaired.
3. They may get better mpg, but remember diesel fuel is more expensive (like $1/gal. more than premium gasoline right now!).

One other thing I wanted to ask and it has less to do with mpg than it does with wear & tear on your towed Jeep's transmission: Is the Jeep Liberty you're towing a 4x4? If so, does it have the old-style hand-lever transfer case shifter or the newer-style electronic switch on the dash to change from 2x4 to 4x4 mode? If it has the shift lever then it will have a neutral 'N' position. Make sure you always put the transfer case in 'N' when it's being towed.

If it has a switch on the dash though, those never seem to have a 'neutral' setting. But if your Jeep's got the switch on the dash and a manual tranny, than just putting the dash switch in 2x4 mode and leaving the tranny out of gear while towing will suffice. But if it's got the dash switch and it's an automatic, things are different:

• DO NOT use a tow bar. EVER! This will prematurely ruin an automatic transmission.
• Put the dash switch in 2x4 mode then back it onto a car dolly (i.e. so only the front tires are touching the road). Big problem: Towing 'backwards' like this is often illegal in a lot of areas. Plus it can be a little unsafe because the towed car's engine weight isn't over the hitch where it should be.
• Use a full car hauling trailer (all four wheels are off the ground).

Main point is, with an automatic you must avoid spinning any 'drive' wheels while towing.

Important: Make absolutely sure you put the transfer case back into anything other than 'N' (neutral) before you unhitch! Else it will roll away even with the transmission 'in gear' or 'PARK'! (I seriously suspect this is the reason the newer electronic 4x4 systems eliminated the 'neutral' transfer case setting!)

This is increasingly not true. Motorhome Magazine puts out a buyer's guide for dingy cars that includes a column for whether a certain car can (according to the manufacturer) be towed on all four wheels with an automatic. When they first started publishing this list, it was basically just the 4x4's with neutral transfer case positions, but now almost every American car and a fair number of imports are towable on all four wheels.

Now granted, some models went from untowable one year to towable the next without any apparent mechanical changes, so draw what conclusions from that you may.

The Saturn line of vehicles was designed specifically to be towed "four down". I towed my 2008 Vue (automatic, AWD) with a tow bar for about 3,000 miles with zero problems.

Yep, The Bob Evans Farms is in rural Ohio, I was just there last month. They were Yankees but nice area nonetheless.

Hey Hail Ants.

thanks for the nice write up. We knew that towing stuff but it never hurts to hear it again and it sure might save some other random reader a buttload of grief.

Our new Jeep has a tiny button you push to put it into neutral. If you listen carefully you can hear a faint clunk and a red led lights up. To me the goofy part is it doesnt STAY lit. It turns off after a few seconds. So, if later you can't remember for SURE if you did it, you gotta undo it and do it again (that or start towing and figure something aint right and/or screw something up). Seems like a bad design to me. Oh, and the first time we towed it was interesting. We got the where we were going, whip out the manual. It told you how to get into neutral to tow. There was NOTHING anywhere in the manual that told you how to get it OUT of neutral. It took about 5 minutes to figure out the critical steps needed.

Oh, and the heat out here in the midwest is interesting. We parked the Jeep in a parking lot about 5pm. The shindig wasnt over till about 10 pm. Go out, get in the Jeep and drive off. Loud clunking sound. Crap, flat tire. Nope, a chunk of asphalt about the size of roll of paper towels had glued itself to the tire and was ripped out of the parking lot surface. Since it had now cooled off, it was well glued to the tire. Took me about 10 minutes of prying, pulling, and peeling to get it off the tire.

Your mileage sounds about right.

We bought a new 1989 32 foot class A, "basement", 454 Chevy. Drove the speed limit 60 to 70 mph, towed a new 89 Honda Civic, auto transx, all four on the ground with tow bar that folded up on the Honda bumper. Mix of mountains and flat land mileage was usually 7 to 8 mpg. If we had a good strong tail wind might get 10 mpg.
The Honda dealer said Honda wouldn't warranty the auyo transx if towed but I'd read in Motorhome magazine that people towed them with out problems so that was good enough for me.

BTW... That sure is low miles for that 97. We sold our 89 in 95 and we had already run up 29,000 miles.

Wow! I can understand the neutral button being tiny to prevent curious and the uninformed from hurting themselves, but once in neutral I'd expect a great big RED light to come on right on the instrument panel, and stay on!