RV MYTHS

[ontheroadagain]

My brain just can't get wrapped around this "weight makes no difference to gas mileage'<br>If we believe this then why does my Toyota RV with a 4cyl only get 12mpg and my corolla 4cy get 30 mpg?<br><br>Riddle me that Batman <img src="/images/boards/smilies/smile.gif" class="emoticon bbc_img">

 

[user 423]

Your Corolla is a lot more aerodynamic so that helps a lot. There's no doubt that weight affects MPG according to the laws of physics. It's just a matter of how much in a specific vehicle and the tradeoffs people want to make.

 

[Seraphim]

Zil

You need additional energy to maintain momentum of a heavier vehicle, which equates to higher rpm therefor higher fuel consumption. How significant is it? *shrug*

 

[Zil]

Up to...2%.&nbsp; Proper driving habits are more important. personally I have not noticed much difference with no passengers or with three, in a 1990 Dodge 300. I realize with big loads there will be a difference, but a necessity like 10 gallons of water? water = 8.45 pounds per gallon.

 

[blars]

Extra weight makes more difference in hill driving, it takes energy to get it up hill that is mostly wasted braking.&nbsp; (I don't know of any RV with regenerative brakes.)&nbsp; But I don't think 50 gallons of water would be that significant.

 

[joey]

I don't use my brakes going Uphill myself.

 

[OldbutDurable]

Interesting discussion. &nbsp;I'm in agreement with on this Owl. &nbsp;I have kept meticulous records of my gas mileage for the past 2.5 years. &nbsp;A total of well over 20,000 miles. &nbsp;I notate each fill up IF there were hills or generally flat or mountainous terrain. (I know it may seem crazy, but hey, go along with me on this for a moment). I also carry 40 gal of fresh water virtually all the time. &nbsp;The mileage difference is, in my opinion, negligible. Fully loaded, up and down hills or mountains, pulling my TT is about 8.4 - 8.7 mpg. &nbsp;Pulling my rig on relatively level ground w/o strong winds about 9.3 -9.5 mpg. &nbsp;It ain't scientific, but it does give me a fairly accurate idea of the actual fuel usage. <br><br>Let's say for the sake of argument, I go on a 2,500 mile voyage (one or two months approx.) &nbsp;Let's also say that half the time is in the mountains and half the time is on relatively flat ground. &nbsp;Let's also take the low end of the mpg's for each. &nbsp;1250 miles at 8.4mpg and 1250 miles at 9.3mpg. &nbsp;1250/8.4=148.80 &nbsp; 1250/9.3=134.40 &nbsp;So in this example, there is a difference of about 14.4 gallons of gas. &nbsp;Let's also say that the price of gas(high end price) is 3.80/gal. &nbsp;That total extra gas is 54.72. &nbsp;While that may be a lot to some and not to others, is it really worth losing (not transporting) the extra water? &nbsp;In my opinion, no its not. &nbsp;Like you mentioned, having to go back out and get them after reaching your destination is a PITA to say nothing of the additional expense. &nbsp;Transporting what I consider to be the 3 vital things I need (water, food, shelter) will never be too much trouble as opposed to saving a few dollars on such things because the pluses far outweigh the minuses.<br><br>ObD

 

[Willy]

&nbsp;I tend to think that the difference in fuel economy, due to weight, might be better expressed as a percentage of GVW, rather than a fixed number.

 

[Zil]

Wow, Owl, and this is only the first myth.<img src="/images/boards/smilies/wink.gif" class="emoticon bbc_img">

 

[travel]

My brain just can't get wrapped around this "weight makes no difference to gas mileage'<br>If we believe this then why does my Toyota RV with a 4cyl only get 12mpg and my corolla 4cy get 30 mpg?<br><br>Riddle me that Batman <img src="/images/boards/smilies/smile.gif" class="emoticon bbc_img">

<br><br>As mentioned, the Corolla is more aerodynamic. A LOT more aerodynamic than a motorhome based on a Toytoa truck. But more importantly, engine size. Not all 4 cylinder engines are created equal. I know you don't have a RAV4, but I can't find MPG stats for a Toyota RV. A 2012 RAV4 with&nbsp;<em>AWD</em>&nbsp;and a&nbsp;<em>2.5 liter</em>&nbsp;4 cylinder engine produces&nbsp;<em>178 HP</em>. Most US 2012 Corollas have a&nbsp;<em>1.8 liter</em>&nbsp;engine producing&nbsp;<em>132 HP</em>. (all information from Wikipedia). The engine size and power, not to mention aerodynamics, will have a mesurable effect on fuel economy. I'd also have to say technology may play a part. IIRC, Toyota motorhomes were only made in the 1980s. Not sure what year of Corolla you have, but I've owned and driven many Corolla of various years, and though they're all very economical on fuel, the newer ones are so technologically advanced and optimized for the best fuel economy.<br><br>But I agree with others, that many utility vehicles and trucks tend to get the same fuel economy whether they are loaded with cargo, or empty. I've personally experienced this with several Ford and GM pickups and vans. Though in this case, I'd have to say that a motorhome on a Toyota truck platform is going to weigh a lot more than a Corolla, substantial enough to claim that the additional weight makes a difference in fuel economy.

 

[joey]

I think the whole point he was trying to make is,lots of people travel to campgrounds without ANY water reserves. When you get to a campground with NO WATER and then have to drive 40 or 50 miles to GET water,you really didn't save any money on gas. &nbsp;Duuhhh!

 

[joey]

This topic has nothing to do with what type or kind of RV you are driving. It is about basic economics!

 

[Zil]

An easy test shown to me many years ago, is to hold a 4x4 sheet of plywood flat against a strong wind. Then think what a 50mph wind would do.<img src="/images/boards/smilies/smile.gif" class="emoticon bbc_img">

 

[twokniveskatie]

Oh, man, Zil, you just introduced surface area into the equation!

When I head out, I have a couple of gallons on board. In the astro, we are not talking a great volume of water anyhow, but im not gonna stock up on water til I get to arizona. Some people may scoff at that but if it saves me a few cents per gallon over 3000 miles, then yeah, that can make a difference. To me.

This has always been a discussion in my trip planning. Ron and I used to weigh factors like the weight of the extra gear on the hitchhaul and in the kayak, and gas mileage lost from wind resistance with the boat on the roof. Should I stock up on canned goods in PA if I see a good price, or will the savings be eaten up by the extra fuel consumption? Everything the scientists in my family taught me says wait about 2700 miles to stock up on sh!t.

Now if the discussion is about the wisdom of getting to a destination and expecting resources to be there....well I learned my lesson the hard way. I only had to backtrack once

 

[Zil]

Gas @ $3.80 gal.<br>Mileage empty @ 15 mpg<br>500 extra pounds. (equivalent 60 gallons water)<br>assuming 2% loss per 100 # (i have not experianced this on the highway. City start and stop is different)<br><br>Yes. For gasoline you would spend $845 compared to $760 for your 3000 mile trip. in theory.<br><br>Driving at 60mph compared to 50mph. Maybe over $900 for gasoline. Soft tires even more.<br><br>using lower grade gasoline is also a mileage killer.<br><br>Driving a mini van with a soft nose compared with a RV or cargo van. That too.<br><br>I'm just saying that based on my 10s of thousands of miles in cargo vans, a few hundred pounds doesn't make much difference.<br><br>I vote for my convenience and comfort.

 

[Zil]

<img src="/images/boards/smilies/wink.gif" class="emoticon bbc_img">

 

[wandering mike]

<p>I get about 9 mpg in a Chevy Class c if not towing a 2500 lb Miata and about 8.5 mpg when I tow it. That is a 5.6% or so reduction in mileage I guess. &nbsp;That translates (I think) to 0.22% reduction per 100 lbs. &nbsp;So for me, it would seem that getting rid of the 30 gallons of liquid I normally carry (split between fresh and gray/black tanks), that would be removing an "extra" weight of<span style="font-size: 13px;">&nbsp;250 lbs at 8.34 lbs per gallon. &nbsp;And if you do the math, it would be a savings of a little over 0.5% savings in mpg. &nbsp;So my mpg (towing) might be 8.54 mpg rather than 8.50 mpg. &nbsp;</span></p><p>Now, since I go about 7000 miles a year, that would be a savings of about 4 gallons over the year and at $3.50 a gallon, about $13.50 in annual savings. &nbsp;Or about what it costs me in gas alone to go 33 miles. &nbsp;Shucks, I will screw around and get lost way more than that many miles in a year, let alone the miles I spend finding water if I don't bring it along.<br><br>All this is some pretty rough estimating too. &nbsp;Am I going uphill or on flat land? &nbsp;who knows. &nbsp;I can certainly understand why people don't much notice any difference in mileage after crunching these numbers. &nbsp;The difference between one tank and the next is probably more the variance in terrain or the extra tenth of a gallon "top off".<br><br>FWIW, the GVWR of the rig is about 13000 lbs as I recall and I usually am pretty much right at that number. &nbsp;Maybe some smart person out there can figure out how that fits in. &nbsp;<br><br>At the end of the day, weight, whether carried or pulled does matter. &nbsp;But not enough for me to worry about. &nbsp;</p>

 

[travel]

&nbsp;<p>At the end of the day, weight, whether carried or pulled does matter. &nbsp;But not enough for me to worry about. &nbsp;</p>

<br><br>I think that sums it up really well. There is probably a difference in fuel consumption, but it's so minor that it's not worth worrying about. In my experience driving trucks and vans, loaded vs empty, I've never noticed a difference. And when you towed a 2500 pound car it only resulted in a half MPG loss in fuel economy, that really helps make this a convincing argument. Thanks for sharing that - it's very useful information.

 

[highdesertranger]

weight does make a difference.&nbsp; weather it makes enough of one is up to the driver.&nbsp; zil as far as cheap gas goes it all comes from the same place.&nbsp; I used to be a road mechanic for an oilfield co.&nbsp; when I would go on a call to a refinery I would see trucks from all the different gas stations filling up from the same tank.&nbsp; the driver might add a bottle of special juice so that company a can say their gas is better than company b but its all the same gas.&nbsp; same goes for motor oil.&nbsp; its all the same.&nbsp; as long as it's conventional and not synthetic.&nbsp; highdesertranger

 

[Zil]

I was in the oil business for a while before moving to waterman. I respectfully disagree. WaWa high test is better than WaWa regular. and Citgo was better gas than GoCheap.