Quote:
Originally Posted by EcoVan
Here's a side shot of the air dam/valance so you can see its shape. The upper portion mostly follows the curve of the bumper and the dam is actually the lower portion.
And yes, I know that aero design is very complicated... I've read Huchos' book along with studying NASA's 1970's Van research that lead to the Aerodyne and other aerodynamic semis, amongst other sources. In the last 10 to 20 years it seems like the whole auto industry is finally taking the subject seriously and instead of just making cars look aero, they are making them actually more efficient. Using air movement to improve aero ( such as the air curtains over wheel wells) is a big step forward.
However, if you take a look at these vans, it doesn't look like GM has done much with these vans since they were introduced. There is nothing to indicate any design work done on the bottom side, the wheel wells , the rear or just about any where else other than maybe the grill inlet and the addition of a small air dam under the bumper in the later years. The rounded edges front and rear are probably the biggest asset of the current design. There isn't even a rear "spoiler" to help air flow fill in the huge wake of the rear end. The body is essentially unchanged since its introduction in 1996, with the exception of some front end changes. Around 2003 the body was moved to a much heavier truck chassis.
To me it looks like it wouldn't take much to make big improvements to this vehicle... alot like the motorhomes. In fact this is a motorhome/ box truck chassis.
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1) GM's corporate policy, historically, is not to 'innovate' with shareholder's money.
2) GM is in the business of making money.
3) One of GM's business operations has to do with manufacturing automobiles.
4) Historically, automobiles burn fossil-fuels.
5) Historically, GM's parent company was also in the fossil-fuel industry.
6) Aerodynamic efficiency threatens fossil-fuel profits.
7) GM has been concerned with 'look-alike' automobiles since 1926.
8) GM 'invented' style obsolescence in 1927 ( Law of the Paris Dressmaker ).
9) GM lets other automakers take risks.
10) If a competitor has a success with some innovation and some GM committee agrees that GM should 'compete' technologically, then one can expect to see an innovative feature appear on a GM product.
11) As of 1987, GM 'produced' a vehicle of Cd 0.089.
12) GM's Aerodynamics Laboratory 'Knows' about low aerodynamic drag.
13) GM's Pontiac Trans Sport van was Cd 0.30.
14) GM's 1992 HX-3 hybrid van was below Cd 0.29.
15) We are not constrained by committees who may value fossil-fuel profits to nameless shareholders ahead of aerodynamic efficiency.
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16) Since aerodynamic drag is governed by frontal area and shape, and frontal area isn't negotiable, on a practical modification basis, we're left with 'shape.'
17) If you were to mimic what NASA did to their Ford Econoline, it would not be unreasonable for you to experience their drag coefficient. I un-knowingly did what NASA did in 1980, and pushed my VW Transporter, from 27-mpg, to as high as 34-mpg. If I'd had access to a fifth gear, I might have seen better.