I went out tonight and showed my wife how to stop our runaway Lexus by holding the stop/start button down for 3 seconds. It worked like a champ.
3 seconds is not a very long time IF YOU KNOW THAT AT THE END OF THAT 3 SECONDS THE ENGINE WILL SHUT OFF.
If you don't know it will kill the engine and you are just trying everything in a panic it's too long to intuitively know it's going to work. Her first impression was that nothing was happening.
Interestingly enough my steering wheel didn't lock so I could still steer. Turning a key off locks the wheel. Also just touching the start button restarted the car whereas you normally have to have your foot on the brake.
In neutral or park my car would still rev to destruction. Someone had mentioned that DBW cars didn't rev beyond about 4k when not in a gear. That's not so on the Lexus.
I forgot to try hitting the brake while under WOT to see if that killed anything.