Ford car production ain't what it used to be

Whall, you see part of the problem is that most of the auto pundits out there, like the people that write the reviews in Car and Driver and such, have not reconciled to the fact that a basic truck is extremely utilitaritian and functional. You can haul plywood, a motorcycle, a couch, move across town, you name it. If you take the tailgate off of it or put on a tonneau, it becomes a fairly fuel efficient single-passenger commuting vehicle - not as good as a sedan of course, but if you don't have to commute a great deal, so what.

There's enough of the new car buying public that recognize this that light and mid sized trucks are always going to sell well in the US.

Personally I can't stand the look of the things - any pickup truck after

1955 looks like a Mexican/white trailer trashmobile in my book - and I'll never be caught dead owning one. I do my hauling with a trailer. But I see the point that dealing with hauling out a utility trailer from the shed and linking it up takes a lot more time than just walking out to the street and tossing whatever piece of crap you need to haul into the truck bed then driving off.

New car buyers generally either buy for image reasons (ie: Prius) or for functionality. Trucks are extremely functional, it's no wonder they are as popular as they are. Most of the auto pundits out there are so focused on the image thing they have lost touch with the functionality end of it.

Ted

Pickups get better mileage with the tailgate up, and no cover. The bed creates a vortex behind the cab that maximizes the aerodynamics. With no tailgate and/or a cover, the vortex cannot form.

---JRE---

Consumer reports debunked that several years ago. They tested a number of different pickups with and without tailgates. The results depended on the truck. Some did better with the tailgates in place, some with them removed. Its not a given that removing the tailgate improves mileage.

From CR Online:

Truck tailgate Q. My neighbor told me to remove the tailgate of my truck for better mileage. What is your take on this matter? A. Several years back, CR said that lowering or removing the tailgate gate made only a marginal difference in gas mileage and in most cases simply does not improve mileage. We are still sticking with that report. Also, the tailgate is part of the structure of the vehicle and when removed, makes the bed of the truck weaker.

You might aslo want to review:

few people know that... i'm impressed.

Image reasons in a prius?

right

Best way to improve mileage when you own a pickup: sell the friggin thing unless you really _need_ a truck and buy a car instead.

It'd be interesting for them to do it with newer trucks, which are more aerodynamic than trucks from "several years ago". While pickups aren't really sold for their fuel efficiency, the better aerodynamics contribute to increased towing capacity and acceleration - things trucks are sold for.

Perhaps if I phrase it this way: pickup trucks are designed to produce less drag with the tailgate up and no cover. That's how they're wind tunnel tested, and if you watch one of those tests, it's pretty easy to see the vortex and resulting slipstream. All things being equal, less drag usually means better mileage.

In reality, it probably has more to do with speed than anything. At highway speeds, you're probably better off with the tailgate up so the vortex/slipstream can form. At slower speeds, it's less likely a vortex will form, so you're probably better off with the tailgate down.

The point being that the OP's assertion that taking the tailgate off or putting a cover on would increase your mileage is more or less a myth.

Speaking of, I'll see your CR and raise you a Mythbusters. :-)

---JRE---

You have any illustrations of this alleged vortex? I'm having some difficulty visualizing how a deep bed interrupting airflow can produce less drag than a smooth surface cover from an engineering point of view. I could see it having weight/force distribution advantages, but from a drag viewpoint, it doesn't seem to make logical sense.

Go check the back episodes of Mythbusters, they did an episode on that. Tailgate up produces less drag than tailgate down. They even did a miniature model test in water and used oatmeal flakes to show the pattern.

Charles the Curmudgeon

Throw some tissue in the back and go for a ride. On many trucks, the tissues will move in a circular fashion, forward along the floor, up the front wall, backwards in mid-air, and back down to the floor. At the right speeds, the debris will continue around and around.

I've seen it with cans, paper, leaves, etc...

Drive around in a pickup with a few dry leaves in the bed. Notice that, while some fly away, many blow upward behind the cab then fall back to the bed towards the back, even at highway speeds.

The thing to remember is that the air caught by the tailgate has to go somewhere. Since it can't go upward due the additional air being caught by the tailgate, it goes down, then towards the front of the bed, then up the back of the cab and back into the bottom of the main airflow... where much of it is caught by the tailgate again. This is called a "locked vortex" and it essentially creates a differential pressure zone within the bed that the main airflow rides upon as it goes over the bed.

---JRE---

Presumably by creating an "air bearing", like the indentations in golf balls are reputed to do. The circulating mass of air moving along with the object is supposed to reduce frictional losses overall.

Whether it works that way with the more irregular shape of of a pickup tray is another matter.

John

Thanks. I guess if it creates a high enough pressure that it could hold the other airflow in a better pattern. Maybe :-)

on 12/12/2007 6:58 PM still just me said the following:

The best way to decrease pickup turbulence would be to use a torneau cover on the bed that starts from the top of the cab to the top of the tailgate, like a military hummer, making the PU a fastback.

but a good generator is about $18,000 cheaper, and will make that power available in real world ac power that you can use without a very expensive power inverter. "Daniel Who Wants to Know" wrote in message news:bye8j.247369$Fc.176252@attbi_s21...

Driving your Generator to work might prove a bit difficult...

Exactly what I was thinking...