what are these?

GeorgeC said:
Not on the trunk, on the top of the liftgate:
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Again, they're almost purely for aesthetics. There may be some fraction of an mpg gained from it due to some reduction in drag, but I'm willing to bet it's minimal in effect especially at city speeds. I'm sure many of the small design items don't add much in efficiency gains by themselves, but may be a "sum of the parts" advantage.

If you're driving the semi trucks with enormous side-profiles and lots of wind turbulence, the side skirts and rear-fairings make a noticeable difference in fuel efficiency. They are traveling at highway speeds 90% of the time, so they reap a lot on the efficiency gains. You don't see those trailer additions on trucks used for local transport because there's not much advantage to them at 45mph.
 
SoonerAviator said:
If it was on an A4, then I'd probably say yes. As I mentioned, they do usually have a function on purpose-built sports cars, so the TT may be functional, but that's not a given.
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As pictured, TTRS.... APR Stage One... 410 HP, 447 ft-lb torque... 0-60 much quicker than I can shift...top speed limited electronically - never been there.


No, I don't think Audi would put one on an A4.
 
flyingron said:
Some spoilers help with aerodynamics by NOT having the airflow try to follow down the back side of the car (especially handy in things that have rather abrupt tails). However, more often than not, they're about as functional as tail fins were.
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Those late '50s cars might not have been aerodynamically efficient, but it sure looks like they had ample lateral stability ...

IMG_1216.jpg


:D
 
wrbix said:
As pictured, TTRS.... APR Stage One... 410 HP, 447 ft-lb torque... 0-60 much quicker than I can shift...top speed limited electronically - never been there.


No, I don't think Audi would put one on an A4.
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Also, if I remember correctly, didn't the early TT have some issues early on with the car wanting to flip or get really loose at high speeds (100+)? I thought I recall the spoiler being added at that point to help eliminate some of that tendency. It was due to the design of the TT that was causing the rear end to get light.

The Corvette never really came with a spoiler, aside from a few "lip spoilers" that were pretty minimal in size because the body design was sort of a wing in itself. The spoilers/wings that are truly functional aren't added until the -R series 'Vettes are included in the discussion, and those aren't for street use. Those are much more intrusive and are adjustable for different tracks/speeds as well.

Nowadays, the sports car designers do as much work under the body to hold the car down as they do on top.
 
Capt. Geoffrey Thorpe said:
Similar to the lip on the tailgate of a pickup - control the vortex behind the vehicle and reduce drag. Auto makers fight for tenths of a mile per gallon improvement in the sticker values.
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It was your earlier post that reminded me to pick up that spoiler for my car. I observed about +1mpg (used to have to work to get high 30.x, now high 31.x comes easily), but I attribute that mostly to the four new and improved tires I put on.
 
Just another terrible trend new cars are following. It started with the Prius imo and now leaking into other designs.
 
to put this in simple terms.....dynamic pressure (force over an area) is pd = 1/2 ρ v2 ......

varies proportionally with density and "velocity" squared.

So, vehicles moving in city traffic.....ain't making much pressure. :rolleyes2:
 
SoonerAviator said:
...but may be a "sum of the parts" advantage.
....
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Read "All Corvettes are Red". In it, you'll see where the design team struggled to remove mean ounces to reduce the overall weight to gain but a fraction of mpg. It all matters and depends on what they are trying to accomplish.
 
silver-eagle said:
Read "All Corvettes are Red". In it, you'll see where the design team struggled to remove mean ounces to reduce the overall weight to gain but a fraction of mpg. It all matters and depends on what they are trying to accomplish.
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Agreed, no doubt that engineering departments can be exhaustive in certain areas depending on the end goal. I just don't know how much the rear spoiler or faux vents really attribute to drag reduction on many vehicles. There are plenty of examples where trunk spoilers exist on the "sport" models, but don't exist on the base models (think '99 Pontiac Grand Prix). I'm willing to bet that most are non-functional other than for aesthetics regarding any performance gain (whether that's traction or fuel mileage).

When it comes to items like active-shutter grills, undercarriage body panels, etc, there's no doubt that those small bits were added to eek out those tenths of an mpg. :yesnod:
 
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