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      10-25-2007, 08:55 PM   #42

Drives: IS300
Join Date: Oct 2007
Location: New York

iTrader: (0)

Originally Posted by swamp2 View Post
(^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.
Me driving a Lexus has got nothing to do with this. I for one is a huge BMW fan as well. The point i'm making is your making a conclusion or assumption right away that Lexus is under rating the IS-F just base on it's performance without even having any real data is ridiculous. And just because you have used a formula to estimate the performance and come up with some data, all that is is an estimation. The real data is what the car will do on actual driving condition, no formula will come up with a better result than that. Now in terms of the figures that Car and Driver came up with, everyone knows that those numbers can change anytime. As a matter of fact, 4 different 0-60 times have been recorder so far for the IS-F that has quite huge discrepancy. Edmunds being the worst at 4.8 secs, Motor Trend at 4.7 and Automobile at 4.6. I just posted and showed you an actual dyno and yet your still arguing that the IS-F is underrated. Reading is fundamental. Everyone knows that the wheel hp is usually around 20% less than the crank hp. Calculate 416hp at 80% and you'll get around 330hp which is close to what Automobilemag came up with in their dyno test. Just because you don't like the results and it favors Lexus, does not mean it's not correct. I could care less if you "dogging" Lexus, but don't be such a fanboy about it. BMW makes some of the best cars out there, but that does'nt mean they're the best at everything.