Do the auto mfrs wind-tunnel test every vehicle they release?

[SZR48207]

Most cars released nowadays look pretty aerodynamic, so I'll give them credit for at least trying to make sedans and coupes cut through the wind.

But vans, trucks, and SUVs are just all over the place. All the large full size trucks are basically shaped like boxes now and they do cheap tricks to get aerodynamics like how GM puts on those ugly bumper front skirts.


Some examples below:

1997 Dodge Dakota. Curvy, flowing lines.

2010 Dodge Dakota. Hard lines, bulky front end.

2000 Ford F150. Curvy lines, smooth edges.

2020 Ford F150. Not only are these much larger in size but look at those brick-like front end proportions. You can't even work on the engine bay on these without a step stool.

Here's an inverse example.
2000 Ford Ranger. Smaller back then, but hard corners. One of these with the 4cyl and 5MT would get an easy 22-24mpg though!

2020 Ford Ranger. Based on a different global platform, but smooth lines, curves, and actually larger than the model from 20 years ago.

I always figured cars would get smoother and more curvy/sleek with technology.. look at all Tesla cars which are extensively wind tunnel tested to reduce drag and noise.

 

[meep]

Regarding the f150 they must. Different models get a different front air dam. And there are ducts right above the bumper that create an air curtain around the outside front wheels. Plus the active shutters, two sets, one in front of the radiator and one in front of the intercooler. Windshield glass is very smooth into the roofline. Underbody is pretty smooth too. its embarrassing to say, I just bought a used Lexus GS v6 to ideally get better mpg around town, and just for fun, and after two tanks of gas, the f150 is still the mpg winner. Auto start/stop dominates over the Lexus in traffic, and the fords a/c seems much better engineered for efficiency, while the Lexus raises Idle rpm and even seems to pick lower gears to raise rpm when the compressor is on - huge comfort-biased programming. I have no doubt the truck saw a lot of wind tunnel time, as well as the lex with a 0.27 drag coefficient.
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[MrHorspwer]

Yes, all vehicles visit the aero lab at one point or another. It's not as important as it once was though. Fluid dynamics performed on 3D computer models can provide most answers before the design is even finalized. Once a design is finalized, it's very difficult to change. Increase in compute horsepower allows automakers to bake aero into the design right from the start, without the expense and effort of putting models in the aero lab.

Also, having smooth lines doesn't make a vehicle aerodynamic. On the flip side, have a large frontal area doesn't make something not aerodynamic.

Aerodynamics is about managing airflow, which means keeping air away from areas you don't want it and moving it to areas you do want it. Air ****s are one way, but look around at any modern vehicle and the location of lower fascias and air ****s. A decade ago, air ****s were tucked way under the front fascia. Now, they're right flush with the fascia. Air under the vehicle isn't desirable. The sooner you push it away from the vehicle, the better, hence, the air dam is now right at the front of the fascia.

meep mentioned air curtains. Spinning wheels are another area you don't want air. If you look in the front bumper of a new Silverado or Sierra, you see two small 4"x1" slots where the bumper and fender meet. This allows a small amount into the wheel area that slides fast moving air around the outside of the spinning wheel and prevents turbulent air from entering the wheel area. This is an air curtain.

On the new Silverado and Sierra, the mirror was moved down to a pedestal on the door. Previously, it was on the door, right where the a-pillar and hood meet. Most important, it is below the level of the hood. Ford does a similar move in a different way with the F150. Where the side glass dips down, the mirror dips down with it, keeping it lower relative to the hood line. This tucks the mirror into an area of slow moving air, limiting it's impact to the aerodynamic envelope.

Putting the air back together is just as important. The tailgate on all modern trucks, right at the top, has a return in the sheet metal. The metal cuts in from the top edge of the tailgate and makes sort of a lip at the top. This isn't only a styling choice. It's an aero choice. GM took it one step further. At the back of the cab, there is a similar return in the design at the top of the back window, only it's done as painted plastic trim with the CHMSL integrated.

Look at the front of the back wheel on trucks and SUVs. Many of them have a small lips of plastic, usually about 1.5' tall and the width of the tire. That's for aero.

Look at the wheel opening of all modern cars. There is a vertical segment that defines the wheel lip, as if someone sliced wheel lip straight down with a knife. That's for aero.

Then there is simple better fit and finish. Look at the photo of the old Ranger and notice how HUGE the gaps are around the headlights, bumper, and grill. Compare that to the photo of the F150 and Ranger, where everything fits together tightly. On the F150 picture, you can even see additional black plastic pieces to close out the area between the bumper and fender.

None of these are cheap tricks. They're all part of a cohesive aero package that are very intentional. Individually, they don't amount to much, but collectively, it's a big contributor toward fuel economy gains.

 

[tcp71]

That f150, with the 2.7l 325HP and 400lb ft of torque, gets better mileage than the Ranger, and any Dakota of any year.

 

[MNgopher]

Just the general look of the vehicle is not everything. Start looking at the small details, and you'll see a ton of work has gone into the aero on even full size trucks.

I've owned all three generations of the F150 referenced above, and despite the smoothed edges/shape of the 97-03 body style, they still delivered much worse fuel mileage than the current generation of F150's.

Delving into the minor details, notice the elevation of the air dam on the front of the F150 in the current generations versus the old - it is substantially lower. The radiator and intercoolers have shutters on them that open and closed based on cooling needs but to optimize aero when possible. There are slots that guide air into air curtains on the outside of the front wheels. The underside of the truck includes shrouds that smooth airflow over the bottom of the truck. The tailgate has a much different shape in an effort to minimize drag. The way many of the body panels overlap emphasize airflow. The way the front of the truck is put together to push airflow in the right directions....

More than willing to bet that despite the appearances, the actual coeffecient of drag has actually dropped significantly from the 97-03 F150's (looks like typically mid 0.4) to the current generation that is somewhere under 0.4.

 

[supton]

I'm guessing they do, if nothing else to look for what got missed--nobody wants to get a vehicle out of development only to find a whistle. Simulation is a great place to start but I'm not sure it's ever the place to stop. Regardless of the technology being simulated (electronics, wind, metals, whatever).

 

[Ws6]

Yes. Looks are NOT everything when it comes to drag. Especially apparent when I see the actual BC's of bullets over radar vs. looking at them in-hand. yes some generalities exist, but you get ogive, secant ogive, and on and on.

 

[RhondaHonda]

Different eras are why the vehicles you posted look different. The mid/late 90s were a time in automotive styling that loved rounded egg- shaped vehicles. Not a great look.

 

[MNgopher]

I don't know... Maybe I'm biased but I liked the look of my old flareside trucks of that era... Still the most reliable vehicles I ever owned were my '97 and '99 F150s with the 4.6. Not the fastest, but reliable and thought they were good looking for the time...

 

[Trav]

I guess this one got away..

 

[DGXR]

With increasing CAFE requirements, I'm sure all new models spend some time in the wind tunnel.

Some aerodynamic designs do not sell simply due to aesthetic reasons. Americans do not like the smooth lines of the Toyota "Hilux" pickup:

So we get something that looks like the Tacoma, boxy and "tough looking"