The inline 6 in the Lexus IS300 is a chain driven engine. This is also the same engine that was used in the late Toyota Supra. I remember reading a review comparing Nissan's 300ZX Turbo with Toyota's Supra Turbo. They mentioned that because the 300ZX's engine was belt driven that it was smoother than the chain driven Supra.... I guess it makes sense that a belt driven engine would be smoother than a chain driven one... It seems that a chain driven engine would be more precise and reliable though... Which is better and are most manufacturers switching to chain drive engines?