This is my reply from an earlier discussion (on SimHQ, though) regarding Murcielago's handling in GT5:
The LP640 Murcielago is big heavy though powerful car. As a race car (and therefore a much lighter version)- eg. in FIA GT1 World Championship- it is undeniably great (although it tends to win in a less twisty/technical course) but if you watch or read the various reviews of the production LP640, there's always a mention of the car's weight and how it will ultimately affect its handling. (NOTE: the race version of Murcielago is based more on the LP670 and is actually RWD rather than AWD)
With my G25 set to 10 (the way like'em) in GT5 and despite the noticeable and constant weight shift, I've noticed that the car has very good traction and just like the Nissan R35 GTR (which is just as heavy and AWD as well), you can floor early out of a turn with no consequence. The only thing I find disturbing is how the weight shift feels on my G25. But until I can afford a Thrustmaster T500RS- I believe the more powerful motor and the dual belt system in the T500RS will eliminate the backlash I'm getting from the G25 especially in regards to weigh shift- I find with the LP640 or any heavy(ier) performance car, in order to go fast you need to be smoother or provide smaller and more gradual steering input.
Just to find out how much different the LP640 is from the rest of the supercar- I did a quick and somewhat comprehensive test on the Top Gear test track. I tested four cars (along with the LP640): the AMG SLS, Lamborghini LP560, Ferrari 458 Italia and the 599. On feel- the 640 feels closest to its less powerful sibling the 560. Compared to the similarly powered Ferrari 599, the LP640 is less sharp (for example entering Chicago) although it exits much better and easier.
For the test, I did a few warm up laps in each car. After which I make sure the HUD and GHOST replay is OFF. The tire is the stock Sport Hard. The oil upgrade has been done to all the car and the brake setting as I do with some of performance cars is set at 4(F):2(R). The car is stock apart from oil upgrade. The best time is take from total of 4 (continuous) lap run in each car. The result:
1- Ferrari 458 Italia [1:17.275]
2- Lamborghini Gallardo LP560-4 [1:17.678]
3- Lamborghini Murcielago LP640 [1:18.182]
4- Mercedes AMG SLS [1:18.247]
5- Ferrari 599 [1:18.434]
So in term of measured performance, the LP640 is comparable to its real world counterpart. The LP560-4, if you look for example on
Fastestlap.com: LP640-LP560 comparison, you'll notice that on most track (including the TG test track) the LP560 is a much faster car. Not to mention that it's right up there with the 458 Italia on what is a pretty technical track. What is interesting is when you compare the cars in GT5 Data Logger (if you haven't already, use the Data Logger, it tells so much more than just looking at the replay).