A new 300-hp, 4.3-liter V8 from the LS430 heralds a name change from GS400 to GS430. As for the GS300, a smooth, powerful 3.0-liter Six and five-speed automatic are standout features, as is a quiet interior. But this competent rear-drive car lacks the dynamic prowess of the BMW 5-Series and Mercedes-Benz E-Class. Handling is competent but unexceptional, braking is excellent. A stability-control system prevents sideward skids. Competing Audi, BMW, and Mercedes models also provide a more supple ride. The front seats are very comfortable; the rear, just adequate.