Why do people do this?

[Isaac Zachary]

I don't know if there's another thread like this. But I thought it might be educational if we ranted a bit on why people do things that don't make sense. I'll start.

I just saw another Prius with a roof cargo box. This seems very common to see on Toyota Prii and Volvo station wagons here where I live.

Now I get that having a box for every once in a while makes sense. If you want to go camping you may not have enough space in a car like a Prius for your kids and your camping gear. Or you're single and need to move. So you slap on a cargo box or a hitch rack and go, kind of like a little Chevy Spark I saw Monday from Florida cruising along with both a huge roof box and a hitch rack with a large plastic tub on it.

But the thing is that it seems most people with a Prius, at least where I live, strap on a roof cargo box permanently. Which makes me wonder why they bought a car known for having a very good aerodynamic shape so that it gets good fuel mileage, and then ruin it with a large permanent box on the roof. Why? Is it that they didn't understand that adding a box defeats the purpose of the car's shape? Is it that they figure they drive slow enough it won't matter?

But that's another thing. Some of the fastest driver's I've seen around here are Prius drivers. Maybe it's the college culture in our town where apparently half the population are college students. Maybe they drive fast, want something they can pack all their stuff in as they go back and forth from whatever state their parents live in and here, and think they're saving money and the environment by owning a Prius.

I have had the chance to talk to a couple of these college Prius owners and have been told that they're disappointed with the fuel mileage, getting upper 30's at best. Mmm... I wonder why.

[redpoint5]

Time is the most valuable asset anyone owns. It's logical to not waste it doing things you don't want to be doing, like traveling down the highway. It's also logical to minimize economic impact by getting an efficient vehicle to quickly travel down the highway.

I'd have to interview each individual as to why they chose a roof mounted cargo box, or why they never remove it.

My brother in law has an enormous roof bag on the minivan when he visits for Christmas. Inside the van is their family of 6 and their large dog.

Personally, I'd go with a hitch mounted cargo carrier if I could, but some want easy access to the hatch area.

[JSH]

I’m a former Prius owner x 2 and current cargo box owner / user.

We got a good size cargo box for the Sportwagen last November. We bought it because we got tired of putting 4 pairs of wet skis inside the car between the rear passengers. It also came in very handy for winter steelhead / salmon fishing and clamming. The wet and stinky waders and gear plus rods / shovels go in the box instead of inside of the car.

The box went on with the winter tires in November and came off with the winter tires at the end of March.

Why buy a fuel efficient car and then put a box one it?

• It is way better than buying a less efficient vehicle without a box.
• It is nice to have storage space outside of a vehicle

Why not use a hitch mounted box?
They are a huge pain. We have a hitch mounted bike rack and we have to swing it out of the way every time we want to access the cargo area. That got old really fast

Why leave the box on all winter?

• Taking the box on and off is a huge pain
• Storing the box takes up a lot of space
• The mileage hit isn’t that bad (2019 – 36.4 mpg / 2020 = 37.25 mpg / 2021 = 36.6 mpg (with box))

Why drive fast with a fuel efficient car?
You are still saving money over driving fast in a less efficient car. Plenty of people buy a car like a Prius to save on fuel. It is a roomy mid-size car that gets great fuel economy. However, they don’t care about eking out the best fuel economy they can. Getting the best mpg they can isn’t a sport / hobby like it is for people here on ecomodder. They are perfectly happy to get 40 mpg driving 80 mph on the freeway. The cost difference between 40 mpg and 50 mpg is small. Driving 10K miles a year and paying $3.50 a gallon for gas the difference between averaging 40 mpg and 50 mpg is $3.37 a week. Less than a coffee.


* If you are a college student or apartment dweller where are you going to store the carbo box if you take it off the car? Rent a storage unit and pay way more than the fuel savings in monthly rent?

[Isaac Zachary]

I think another thing is lack of options.

Theoretically it would be best to buy a vehicle sized for what you need (example: Prius v) and not a smaller one you have to permanently attach cargo boxes to. But there has been a pretty big void between small +50mpg cars and -20mpg cargo haulers. And although that's changing, that's not going to help the used car market for some time.

I find it hard to believe that adding a cargo box at worst hurts fuel mileage by only 0.65mpg and at best increases it by 0.2mpg.

[Piotrsko]

Well Thule says their cargo boxes are aerodynamic whatever that means.

I find younger people don't really grok anything, it's all superficial.

I would guess I was superficial back when I was 20. Can't recall that far back.

[JSH]

Originally Posted by Isaac Zachary

I find it hard to believe that adding a cargo box at worst hurts fuel mileage by only 0.65mpg and at best increases it by 0.2mpg.

That is just my recorded fuel economy, not a scientific experiment. I log every vehicle expense on every vehicle including every fill-up. Those are my averages from November - March for the years in question. I have no way of knowing if the driving was similar. April - August 2021 I we have averaged 35.25 mpg. Maybe the summer tires offset the cargo box. Either way I'm not seeing a huge hit from having the box on the vehicle.


This is the box I have:

Yakima Rocketbox 11



My question is why do cargo box makers design them to be put on backward? The right side in the picture above is the front. For best aerodynamics it should be reversed with the round side in the front gently tapering to the rear. However the way the mounting works I can't flip the direction and still open the rear hatch.

[redpoint5]

Originally Posted by JSH

My question is why do cargo box makers design them to be put on backward? The right side in the picture above is the front. For best aerodynamics it should be reversed with the round side in the front gently tapering to the rear. However the way the mounting works I can't flip the direction and still open the rear hatch.

It's been discussed before. Since you're in an industry that designs things that are required to consider aerodynamics, perhaps you could help answer that.

You think Yakima knows nothing about aerodynamics, or do you think they have to make them backwards to satisfy ignorant humans?

[JSH]

Originally Posted by redpoint5

It's been discussed before. Since you're in an industry that designs things that are required to consider aerodynamics, perhaps you could help answer that.

You think Yakima knows nothing about aerodynamics, or do you think they have to make them backwards to satisfy ignorant humans?

I think is is the later option. Stylists and marketing types trump engineers in most discussions. Most people think the front profile is more important than rear profile so companies market to those perceptions.

I have an older box and the newer Yakima boxes have some improvements.
This is the newer and more expensive version of my box:



The rear is sloped up to allow the box to be positioned farther back on the vehicle and still have the hatchback lift fully. It also allows the mounts to be centered on the box instead of biased towards the back of the box.

[Isaac Zachary]

The ones that I normally see on top of Prii aren't those thin aerodynamic Thule ones, but are bigger and boxier like this one:


.

[JSH]

Those would hit fuel economy more but a 35 - 40 mpg Prius with a box is still better than a 25 mpg CUV.

The bigger the box the more of a hassle it is to take on and off and the more space it takes to store. All the more reason to leave it on.