Occupants of the 2007 Lexus GS 450h will appreciate a ride that's quiet except for optional run flat tires – they've been on the road for a few years now, we know they work and their benefits, but hopefully engineers are now working on making them quieter. Rattles and squeaks have been eliminated from the cabin, and under normal driving conditions, engine noise is so muted and distant that you may think it's coming from the car next to or ahead of you. However, more forceful jumps on the throttle unleash higher decibels from under the hood, but the sound is refined and not overly intrusive.