This works on my LS460, so I am assuming it probably works on other Lexus models with keyless ignition.

Sometimes it's a pain to need to press the brake pedal when starting the engine; say the driver is out of the vehicle and the passenger wants to start the car to run A/C, etc.

Here's a workaround: Press the Engine Start button once to go into ACC mode, then press and hold it for 15 seconds to start the engine.

Note: You still need to have a key fob in the car to start the engine, this only eliminates the need to be stepping on the brake pedal.