Weve all seen the basic ones which you put the bhp and weight in and it give you an aproximate 0-60, top speed etc but is there a more accurate one that you can put in each gear ratio and final ratio?

You would also need to input the torque curve for the engine for it to be of any real value.

Still a bit meaningless without taking account of aerodynamic effects, particularly for something as brick-like as a Seven.

I know but surley some brainbox must have already done that?

I use Car Test:

http://www.cartestsoftware.com/cartest4.5/index.html