Considering until recently her car was the 335xi it will be to pay close attention because Im curious to see what she perceives the differences to be and particularly if she finds it "less zippy" (her term for "needs more torque"). My guess is she will find it zippy enough
I never really mind letting people drive. I allowed friends to drive the GTR, my SC NSX, modded Vette and 911s. The one exception would probably be if I had something *really* collectible since at that point the risk would be too high.