[jdlowery]

Others have already given you some good advice so I'll add to the opinions. You really have to know your kid. If she's a responsible driver then 306hp (don't forget that extra 6hp) may be OK. If she's like I was at 16 then don't do it!
I may be one of the few that responds that actually owns an IS350. I've had it since new in 2007. It's a quick car but it's not a Turbo 911. I've gone way faster than I should have in my IS350. The suspension is a little too soft at high corner speeds but I've been tempted to track it. My kid is about the same age as yours and he has his eyes on the IS350. Of course he can drive it but his daily driver will be a '70 VW Bug with no freeway driving. Good luck with your decision.