NEW YORK — Acura, Infiniti and Nissan introduced new models at the heart of their vehicle lines at the international auto show here last week, while Lexus unveiled a technology-laden, gasoline-electric hybrid version of its upcoming LS top-of-the-line model.

Here are details of the three Japanese automakers introductions:

• Toyota Motor Corp.'s Lexus division is taking direct aim at Mercedes-Benz and BMW, unveiling a 430-horsepower gasoline-electric hybrid sedan aimed to place Lexus at the top of the luxury food chain and boost the company's hybrid market share.

Toyota calls the 2008 Lexus LS600h L the most technologically advanced vehicle in the world, and they may not get much argument on that point. Its list of appointments stretches from all-wheel drive to a massaging and reclining back seat. Its safety system includes a camera on the steering column that sets off an alert if the driver is not looking at the road when an accident appears imminent. It can even parallel park itself.

Lexus general manager Bob Carter said the LS600h L would appeal to the top 10 percent to 15 percent of Lexus LS sedan buyers, and will compete head-on against the V-12 sedans from Mercedes and BMW.

• Honda Motor Co.'s Acura division revealed two sporty-looking SUVs: the all-new compact RDX and a major restyling of its MDX midsize SUV. Acura executives called the MDX a concept vehicle, but they admitted it looks very much like the model that goes on sale this fall.

The RDX goes on sale this summer. It features Acura's first turbocharged engine, a 2.3-liter four-cylinder that produces 240 horsepower.

Acura is Honda's luxury brand, and the RDX is the first new model from the automaker's new global truck architecture. The new Honda CR-V that goes on sale later this year will share the architecture, and the company's other trucks — the MDX, Honda Pilot, Honda Ridgeline and Honda Odyssey — will move to it as the current models are replaced. An architecture is a set of systems and components that forms the basis for a wide variety of vehicles.

• Nissan Motor Co. showed auto show attendees the 2007 Altima midsize sedan, the replacement for the brand's best-selling model. The Altima was the fourth-best selling car in the United States last year, with 255,371 sales.

It's the first model to use the new D architecture, which will form the basis of many Nissan and Renault cars around the world. French automaker Renault owns a controlling interest in Nissan, and the two companies have pooled their product development efforts.

• Nissan's Infiniti luxury brand showed a significantly restyled version of its G35 sport sedan. The distinctive looking G35 helped sparked Infiniti's recent sales resurgence when the sporty model debuted in 2002. The new model features a 3.5-liter V6 that Nissan executive say will produce more than 300 horsepower. The new G35 is longer and slightly wider and taller than the car it replaces.