View Single Post
      10-25-2007, 08:12 PM   #38
Lieutenant General
swamp2's Avatar

Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

iTrader: (1)


Originally Posted by gbb357 View Post
You've got to be kidding me!? How do you figure it's under rated? You'll see that the results is comparable to what they got for the RS-4 with 420hp. And remember that the U.S. spec RS-4 is almost 4000lbs and the performance figures are quite similar. And also, Car and Driver has always gotten the best performance figures on any car compare to any other magazines. So the 0-60 @ 4.2 secs and 12.7 1/4 mile they got for the IS-F is no surprise. In other words, i'm almost sure this car is not underrating it's hp and weight figures. Besides, it's not like they could hide that or get away with it anyway. Car and Driver already has the full test on it and all the specs as well.
(^Nice use of all bold font.)

I figure it is under rated by using multiple methods. Don't attack my conclusions here just because you drive a Lexus. Try to argue your points with more evidence, science, logic, etc.

The reasons/methods I have used to determine the car is under rated are scaling on power to weight. Power to weight ratio is one of the best indicators of acceleration performance (F=ma, more or less). The M3 has a substatntially better power to weight ratio and especially considering the additional power losses from an automatic transmission (meaning power delivered to the ground divided by weight, which is what really matters). The M3 has been dyno-ed at 373 rwhp(link). So we have:
  • M3 lb/rwhp = 3648lb/373 rwhp = 9.8 lb/rwhp
  • IS-F lb/rwhp = 3725lb/333 rwhp = 11.2 lb/rwhp

That is a whopping 13% difference which equates to about an extra 50 hp if the cars weights were to be equal. You think this does not matter.. You think it makes sense that the IS-F is faster??

Next I used physics based simulation software (the same basic techniques used to design the majority of the cars we all drive by the way). This software is called CarTest and I encourage you to play with it (well maybe not, it probably requires an engineer or scientist to get decent results from it)

The IS-F figures vs. the Audi are still suprising to me. The RS4 should absolutely get the jump on the IS-F 0-60 with its AWD. Furthermore the 114 mph trap speed for the quarter is more of an indicator of the hp rather than the ET. This thing is really moving at the end of the 1/4. Again this does not add up given its delivered power to weight ratio.

The substantial besting of the M3 by the IS-F to 100 mph is also quite suprising given its the same reasons outlined above (less power to weight, more weight, more lossy transmission, etc.)

So in conclusion stop thinking I am "dogging" the IS-F; the numbers it is delivered, at least straight line numbers () are astounding. So astounding that something just does not add up.