Packing Light Vs. Fuel Economy

It has been suggested that there is a direct savings via fuel economy to be gained by paring down gear, food, etc to the minimum necessary. I suspect there are cases where this is true, but there are other factors to consider that are far more important. And I suspect any savings in fuel cost is minimal.

First, paring down gear is a great way to simplify your life. In our view, that is the primary reason for not packing enough silverware to enable you to avoid washing dishes for a week, or enough dishes to host a once-a-year get together (unless that is the only time you go camping). Having less stuff means you didn't spend money on stuff you don't need, and when you go to look for something, you generally can find it right away. For us, less is more; simpler is better.

Second, over the past year our van gained a fair amount of weight. We added a plywood deck for Lana's bed (creating storage space underneath for our new KingCamp canopy, a new privy shelter and up to eight firelogs), we added a plywood bulkhead behind the front seats, installed an ARB awning and solar panel on our roof, created new storage space below the van's roof, bought an extra camp chair (so Lana would quit stealing ours) and generally made lots of tiny improvements, all of which added tiny amounts of additional weight. The solar panel and awning also slightly affected our van's aerodynamics, creating additional drag. And we have been stocking up on various food items and supplies, either because they can be difficult for us to find on the road, or because we know where we can get some things WAY cheaper than in most places that we find while traveling. We have no idea how much all that weighs, but quite probably 100 pounds or more (the ARB awning is not light).

We've monitored our fuel economy via our van's built-in gadgetry, and it is hard to say if we are actually getting poorer fuel economy than before making these modifications. That is partly because we've learned that our van's mileage is greatly affected by air temperature. For instance, in freezing weather the fuel economy drops considerably. This is because newer engines are so efficient that there is less waste heat to use to heat up the cabin. To get around this, our van has a built in electrical heater that engages when engine heat is insufficient to supply the desired amount of heated air to the cabin. When that thing is running, the fuel economy goes down pretty significantly.

Generally, in warm weather we average around 23 mpg, and that includes a lot of driving in the mountains. Right now we are getting close to 25 mpg, having just changed our oil and driving where grades rarely exceed 3%. Before the oil change we were getting around 22.5 mpg in mountainous driving in cooler weather.

So, if we assume that the changes to our van are responsible for losing .5 mpg, what does that 2% reduction cost us? Strictly in term of fuel cost, that could represent an added expense of a little more than 2/10th of a cent per mile (based on gas costing $2.50 per gallon). That roughly means that we will burn an extra gallon of gas for every 1,000 miles we travel (at 23 mpg, we use 44 gallons of gas in 1,000 miles: 2% of 44 gallons is less than 9/10ths of a gallon).

So what do we gain for this extra $2 in expenses for every 1,000 miles that we travel? We certainly have more comfort and convenience. As a result, Lana is happier, Alea is happier, and I'm happier. That alone is worth it. In 1,000 miles we typically will travel for close to three weeks. We'll buy groceries every three or four days. We don't track that cost, but let's guess that we spend $30 a day (not including dog food), or about $600 in 1,000 miles. We often travel in very rural areas, where grocery prices can be dramatically higher than in most urban areas. If carrying extra food to avoid some of those higher prices saves us even 10% on our grocery bill, that's close to a savings of $100 per month. But I suspect our actual savings is probably double that or more.

There are a few non-food items that we stock up on because we have brand preferences, and they can be hard to find on the road. For instance, we use the cannister-style Kleenex tissues. They are more expensive, but far less bulky than cube-style tissues. We keep one in the galley, one in the cabin and one in the van. About 30% of Walmarts carry them, and they seem to be available in all Target stores. At times we've driven considerable distances out of our way to find these or other specific items. It costs us 11 cents per mile in fuel for these extraneous shopping trips, so driving 20 miles out of our way can cost us an additional $2 in expenses. But if you factor in the wear and tear on the van and camper that cost is a lot higher. I don't know what the current average cost is, but I know in the past that the IRS would allow you to deduct around 50 cents per mile for unreimbursed business expenses, which factors in fuel, maintenance, insurance, depreciation, etc. From that perspective, the 20 mile side trip could actually cost more like $10.

So, I agree with the notion that it is best to travel with minimal gear. But at the same time, we live in a Goldilocks world, so how much and what gear is "just right" will always be a personal decision. To us, a more important consideration is how easy is it to access the gear that you do have when you need it?

But I don't think it is wise to be minimalist about supplies (having extra food and water on board if you have a mechanical break down is always reassuring). Though that needs to be balanced against how much space you have for storing those supplies. For instance, we have sufficient extra room in the bottom of our deep storage bins that we buy an 18 pound bag of dog food (which lasts about 3 months), instead of the 6 pound bag (which lasts about a month). That saves us about $16 every three months, plus we make one third fewer trips to find a Petco or Petsmart, in order to get a brand that we know will not cause Lana to have skin issues.

Regarding the fuel economy of our van, I can pass on the following tip. Our fuel economy is best when engine RPM is lowest. Around 38 mph is a sweetspot for us: the engine runs at about 1,400 RPM. Mileage drops slightly as speed increases, until the point where the transmission shifts up, then the engine RPM drops and the mileage increases. This may not be a typical situation, since our van has better low RPM torque than most vehicles. But I suspect most folks will find engine RPM a good way to determine your best fuel economy at various speeds, assuming your vehicle has a fuel economy calculator to help you figure that out.

 

When I asked this question I was focused on weight as a safety issue, not an MPG or $ issue, though some folks did ready my poorly-drafted question as being an MPG question.

I can't imagine adding so much weight to the TD that it would impact mpg/$ in any meaningful way. Seems like it makes far more sense to carry extra stuff on the trip, rather than go shopping for that stuff while on the road. (Granted, some stuff you can't keep "extra" of - like ICE!)

And it doesn't sound like there's any negative impact on safety from filling the TD with stuff, provided we follow Cary's guidance (which I need to review, but I'm sure I'm not even close to violating any guidance).

Then again, both of these conclusions change dramatically if you drive your rig north of 60 mph, I am guessing. And certainly if you drive north of 70 mph. MPG will plummet as will safety.

Happy camping!! We're off to Henry Coe State Park tomorrow. Best wishes to all for Memorial Day. I'll take some time to remember my loved ones (and yours) who served our nation (though I don't have any close relatives who died while serving).

-Al

 

Yeah, since it is rare that we are ever in a hurry, it is equally rare that we drive over 60 mph. But I believe you are right that gas mileage declines more quickly the faster you go, especially uphill.

At one point we considered getting a Dometic ice maker in the hopes of greatly reducing our need to buy ice. But we imagined that would be an expensive effort that would ultimately end in failure.