Quote:
Originally Posted by GretchenGotGrowl
Different color calipers, so I am guessing they are different cars. GM did say the A8 would be faster than the M7 and that the Z07 produced more downforce than any car they had ever tested. If the Z07 package has 200 lbs of downforce (who knows what it really is) at 100 MPH, that's like having another full-size male occupant...not to mention the drag that must go along with it. That can significantly impact acceleration. So, maybe what we are seeing is that A8s with less aero accelerate faster. They won't handle the twisties as well, but they may be really good in a straight line.
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Quote:
Originally Posted by DGthe3
Yes. However, you were originally talking about straight line acceleration. And in that situation, there is a difference. For the car with the passenger, you have increased the mass by about 90 kilos (200 lbs). In the downforce car, you've probably added something between 90 and 300 newtons of drag (translating to 20-70 lbs), depending on the aerodynamic efficiency of the added aero-bits. For reference, at ~170 mph, most cars have something like 400-600 lbs of aerodynamic drag. I have no clue how much propulsive force a 2015 Z06 generates at the speed where it might be generating 200 lbs (net) of downforce. Which means I am as far as I can go with guesstimating numbers.
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I agree, we don't know what the downforce or drag are. I will say that the Porsche GT3 is supposed to have about 700 lbs of downforce at 186 MPH. Given GM's penchant for comparing the Corvette to Porsches, the Z06/Z07 may be higher than that. Of course, the drag will be higher as well. So, you expect slower acceleration given similar power-to-weight ratios. Which goes back to the point I was trying to make to Newmoon. He should expect a difference between a M7 with Z07 package and a A8 without. It is all guess work until official coefficients and downforce numbers are released for the different aero packages.