Ok, I'm going to say this as follows:
Ford Mustang GT for grip = suicide and so was the BMW M3 E46. Better off with a Lancer Evo X or Subaru WRXST Impreza or Porsche 911 Turbo.
Drag: the Pagani Zonda F can actually do 5.5 seconds if you set it up right for pure drag and I have managed over 1600ft in a wheelie for it so stick with it.
The R35 is quite good for speed, but I still recommend the Porsche 911 Turbo
As for drift, you have the two best cars.
I wish I could give you a full detail blueprint for each of the cars, but this is because:
1) I haven't kept those cars for those modes
2) I am currently working on a walkthrough of blueprints for a number of cars as it is which will take time.
Status = Part Time. [b][color=red][size=12]I am the car expert! So I've been told. lol[/b]
Check it out