If anyone thinks a .28 drag coefficient is 'good', then they may not be aware that a .27 Cd was achieved with the 1921 Rumpler, .25 with the 1933 Dymaxion, .21 with the 1935 Tatra T77a, .26 with the 1951 Hotchkiss Gregoire, .19 with the 1954 Alfa Romeo BAT7, .137 with the 1985 Ford Probe V, .19 with the 1998 Dodge Intrepid ESX2, and .16 with the 2000 GM Precept. All of thse are capable of seating 4 or more adults.
A wagon, lends itself to a longer, smoother taper and thus should be easier to achieve a low drag coefficient than a car.
Given the above, .28 is a brick. That's like soooo 1920s. Our cars are way behind the times.
Imagine a VW Jetta TDi wagon with a 130 horsepower turbodiesel. Give it a sufficiently tapered body for a .16 Cd. 90 US mpg at 65-70 mph highway speeds would not be out of the realm of possibility.
Give it the 5.0L V10 diesel that the Tourag uses, with all 310 horsepower and 540 lb-ft of it, and over 50 mpg would still be a possibility.
The Touareg, with its horrendous .41 Cd, ~29 square foot frontal area, and 5,300 pound curb weight, gets like 20 mpg combined, 23 highway. Imagine a wagon with 2,800 lbs curb weight, .16 drag coefficient, and about 22 square foot frontal area, with this engine. It would need about 1/3 the horsepower to maintain 70 mph, as the Touareg, thus using about 1/3 the fuel per unit of distance travelled(slightly less, due to the less efficient engine operating point from decreased horsepower requirement).
Now who would want a family wagon that had a 310 horsepower V10, did 0-60 mph in under 5 seconds, ran on B100, topped 170 mph, and got over 50 mpg combined? All possible by significant reductions in aero drag.
Cars available today are a joke. Their drag coefficient hasn't changed significantly from the ~.4 of the musclecar era to the ~.32 of today. Consequently, fuel economy is not much better.
I didn't mean to imply that a CD around .30 was "good" just that compared to other vehicles made now days it is below average. I completely agree that it is not "good".
My understanding is all the VW TDI's come with LRR tires, there were two common ones, the Michelin Energy's (what I have) and I don't remember what the other one was. I am not sure what is on the gasser Jettas.
If you compare it to what the automakers are willing to sell us, then you make a very valid point. With the discontinuation of the Honda Insight, the most aerodynamic cars sold to the american public by mainstream automakers today are the Toyota Prius, Infiniti G35 with aero package, and Lexus LS 460, all with a .26 Cd.
The LS 460, with a 380 HP V8 and 4,250 lbs curb weight, gets 27 mpg highway. Vehicles with this size engine and curb weight typically don't do no better than 20-22 mpg highway. This 27 mpg is like the same highway mileage as a V6 Pontiac Grand Prix with 200 horsepower, about 800 pounds less weight, and a Cd ~.31.
Why can't we have a car with a 300+ HP V8 which gets 35+ mpg highway? People would buy it, and it's possible.
I just don't understand why the car comapnies won't offer fuel-efficient versions of existing cars and trucks to serve us Gassaver nuts. I personally paid a $5,000 premium for my sadly disappointing F350 6.0 liter diesel.
I would have paid the SAME premium for the smaller 4.5 liter engine Ford puts in its Class 4 &5 LCF trucks. This engine could deliver the 25 mpg mileage I want.
Why doesn't Chevy / GMC offer the 5.2 liter 4 cylinder Isuzu diesel in addition to the 6.6 liter Duramax V8?
Why doesn't Dodge offer a 3.9 four cylinder version of the Cummins 5.9 liter straight six? They made the 3.9 liter for marine applications.
Damned frustrating, if you ask me.
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I just have dial up, so I chose to simplify my search by only looking at a single year, but as you can see, there are alot of small diesel trucks that have been made, and altho the EPA site doesn't go back, I know that there are alot more older ones yet, like the VW truck, but you have to admit, it had a 500lb cargo capasity (same as a chevy s10) it's still built light, and really, going with something like a station wagon for alot of peoples needs might really be the best choice that I can see.