How cheap is a cheap diesel car? I drove the 260 miles to SEMA
in a 2009 Jetta TDI. It avg 45 mpg at 75 mph. Return trip avg
47 mpg at 75 mph. First 50 state certified diesel car.
Around $22,500. Don't Nox if you haven't tried it! Bin there,
done that! Track my tiers!
jd
That is the problem right there. 75 MPH cannot keep up with
traffic let alone pass.
We don't have any stinking diesel car. :)
Paul Lamar
Paul,
You don't get it! I said I AVERAGED 75 mph for the entire 260 mile
trip each way. Do you know how fast you have to drive to average 75
mph from point A to point B including stop and go, lights, slow
freeway traffic? The Jetta will run WAY over 120 mph. Smokeless and
seamlessly.
jd
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So John Dinkel tell me again how this made in Mexico, 3285 pound,
aerodynamic brick, econ shit box can do 120 MPH on 120 HP. Perhaps
down the side of a mountain or dropped out of the back of a C130?
The other magical thing about it running flat out it gets 4 to 5
MPG better at 75 MPH than the EPA was able to squeeze out of it at
50 MPH or so. Frankly your creditability is suffering. This real
data is exactly how I imagined diesel cars. Smelly, under powered,
econo boxes burning too costly fuel.
Do you want to tow or do you want to go? :)
No more messages! My diesel car is better than your what ever.
Paul Lamar
The EPA ratings seem to be underestimating the actual efficiency in
mpg. That said by owners of the 2009 model, who are getting higher
mpg's.
Is 120 MPH on 236 foot/pound torque attainable? The RX 8 has a bit
over half as much.
Please explain to the uninformed.
Alfonso
Torque has nothing to do with top speed. HP has everything to
do with top speed but it takes cubed HP to go fast.
HP is drag times velocity. Aero drag is velocity squared.
Road HP is 130 HP times 550 or 71,500 pound feet per second.
120 MPH is 176 FPS.
Total drag HP is therefore 71,500/176 or 406 pounds at 120 MPH.
Drag above that number you will go slower. Drag below that number
you will go faster.
Frontal area is 30 square feet. Six feet wide by five feet high.
Drag factor is .3. A Prius is the best sedan in the world at .26.
The Jetta is no Prius. Dynamic pressure is 9.36 pounds per square
foot at 60 MPH.
Aero drag at 60 MPH is therefore 9.36 x 30 x .3 = 84 pounds.
Car rule of thumb: Aero drag and rolling drag are equal at 60 MPH
so rolling drag is also 84 pounds at 60 MPH. At 120 MPH rolling drag
is 168 pounds. Rolling drag is a linear function of speed.
This is a conservative estimate for such a heavy small car.
Rolling drag is probably higher.
Aero drag at 120 MPH is 30 x .3 times .0026 (sea level air density
factor)
times 120 MPH squared or 336 pounds. Plus 168 pounds rolling drag is
336 + 168 or 504 pounds total drag at 120 MPH for a Jetta.
Perhaps it will do 115 MPH at sea level. Maybe more if turbo'ed at
4,000 foot altitude. Some of it is high desert on the way to Las Vegas.
Perhaps John had a 40 Kt tail wind :)
Paul Lamar
Thanks a lot for the insight! I'll keep it.
Alfonso
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