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Hmmmm, quick look at 60-0 times in Road and Track Road test summary:

BMW M3 GTR - 94 feet - $470K
Corvette C5-R - 96 feet - $420K
Viper SRT-10 Comp - 96 feet - $100K
Porsche 911 GT1 - 98 feet - $1M

Nothing else in double digits....

Enzo - 109
Z06 - 107
Gallardo - 110
Saleen S7 - 125

Different conditions/drivers/etc/blah/blah/blah, but still impressive
 

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I'd be interested to see what a Mosler MT900 and Mosler Raptor do. I'll look them up and get back to you guys.
 

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MT900 has 70-0 listed at 149 feet. Not sure what that translates to for 60-0. My best guess is about 115 ft, but can't be sure. Doesn't really make sense. It's the same weight as a fed elise, has softer, wider rubber, and for sure more downforce.

The raptor is listed at 121 ft.
 

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For reference, this old article compares a Honda-engined S1 versus and a Ford Cobra R. It recorded 60-0 @ 119 feet. Not sure how different the brakes are other then ABS, but the S1 w/Honda was 350 lbs lighter then ours.

I think when the mags do some official stats, the number is likely to be in the 110-130 range which is very good, but not exotic.

http://www.sportcompactcarweb.com/features/0205scc_coblot/
 

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Based on the quarter mile times the GTech gives compared to a real dragstrip, I'm wouldn't be too confident in its' precision. If I recall correctly, it's usually at least tenth or two off.

And different testing methods can give far different results for braking. I think C&D begins measuring braking distances the moment pressure is applied to the pedal, not when deceleration begins or when the speed drops to 60mph (from 60.5mph or whatever it actually was in the test).
 

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There was a long sting on this already, no way did the Elise do 93 feet on Street tires, doubtful on race tires. I would really question the test parameters or measurements.
 

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transio said:
I'd be interested to see what a Mosler MT900 and Mosler Raptor do. I'll look them up and get back to you guys.
Or an Ultima GTR. :)
 

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93 ft for 60-0mph braking means that it pulled an average of about 1.3g.

If the speed measurement for 60mph was high by just 4mph, the force of braking was really 1.1g which would imply a real 60-0 braking distance of about 109ft.

As you can see, accuracy in the speed measurement is very important. The equation describing this is (remember to use consistent units):

x = v^2 / (2 * a)

where x is the braking distance, v is the starting velocity and a is the deceleration. Since the original velocity is squared, the accuracy of the measurement of the velocity is very important. As the tester said, they are still nailing down the initial velocity measurements so it is probably best not to make much of the results until the error on that measurement is very small.

The moral of the story is: Whenever someone quotes you a number you should ask what the error on that number is. If they can't answer this question well, their number is somewhat meaningless. Nothing is ever perfectly measured...so knowing the error on a number is key in understanding the number.
 

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Nochmal said:
93 ft for 60-0mph braking means that it pulled an average of about 1.3g.

If the speed measurement for 60mph was high by just 4mph, the force of braking was really 1.1g which would imply a real 60-0 braking distance of about 109ft.

As you can see, accuracy in the speed measurement is very important. The equation describing this is (remember to use consistent units):

x = v^2 / (2 * a)

where x is the braking distance, v is the starting velocity and a is the deceleration. Since the original velocity is squared, the accuracy of the measurement of the velocity is very important. As the tester said, they are still nailing down the initial velocity measurements so it is probably best not to make much of the results until the error on that measurement is very small.

The moral of the story is: Whenever someone quotes you a number you should ask what the error on that number is. If they can't answer this question well, their number is somewhat meaningless. Nothing is ever perfectly measured...so knowing the error on a number is key in understanding the number.
This of course also applies to the test that magazines conduct. However we make the assumption that they employ the same methods (and therefore accuracy) in all their test.

My question is why do I see official numbers for everything but braking distance?

Isn't stopping ultimately the most important thing:confused:
 

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Derek said:
This of course also applies to the test that magazines conduct. However we make the assumption that they employ the same methods (and therefore accuracy) in all their test.

My question is why do I see official numbers for everything but braking distance?

Isn't stopping ultimately the most important thing:confused:
Actually, the fact that they use the same equipment doesn't take care of all the errors in a measurement. While it does is take out any systematic shifts in their measurements, it doesn't take into account random inaccuracies in the measurements. If their speed measurement apparatus is only good to +-4mph then their braking distance measurements are only good to that precision (an error of more than 10 feet on the braking distance measurements as you see in my first post) and any comparisons of the distances have to take that into account. They rarely quote errors on the measurement apparatus though, so we don't know if we can compare braking distances with a precision of less than 10 feet or not.

Errors are a pain in the ass...I suspect this is why the mags leave them out. However, you should demand to know the errors if you want to actually compare the numbers at any level of detail.
 
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