A friend and I had a '68 GTO that we street raced (alot). It started out at 3845 lbs and we got it down to 3100 lbs even after we added an eight point roll bar. A/C has to go and not just under the hood, under the dash as well. Seats replaced, cruise control, windshield washer motor, you name it. Start looking at every component of your car and think about if you need it or not or if it can be modified to be lighter. How often do you use your parking brake? That stuff wieghs quite a bit. But think of safety as well. I saw some very fast cars that had brakes that wouldn't stop a riding lawn mower let alone a 3500 lb missile.
But I'm of the same opinion of why you would do this to a Lexus. If it has already been misused and abused I might think of doing the same thing.
I just thought of something else, be creative. Did you know that Dodge didn't have window mechanisms in the Hemi Darts in '68? They used what looked like seat belts to raise and lower the door windows, which by the way were Lexan.
Wick