Nissan's best-selling model is unchanged for 2004, as a revised '05 model awaits a spring 2004 introduction. Altima shares its basic design with the Maxima, but costs less and offers a 4-cyl engine vs. Maxima's exclusive V6 power. Altima comes as the 4-cyl 2.5, 2.5 S, and 2.5 SL models. The top-line 3.5 SE has a V6. All offer 5-speed manual or 4-speed automatic transmission, except the automatic-only 2.5 SL. Leather upholstery is standard on the 2.5 SL, optional on the 3.5 SE, and unavailable on other models. All Altimas have 4-wheel disc brakes. All but base 2.5 models offer a Braking and Airbag option that bundles ABS with front torso side airbags and head-protecting curtain side airbags; traction control can be added on 3.5 SE automatics. SEs come with 17-inch wheels vs. the other models' 16s. The 3.5 SE is available with a variety of sport packages that include such features as a sunroof, rear spoiler, premium audio, heated seats, and xenon headlamps. The '05 model will feature slightly revised exterior styling and a redesigned interior, along with a new 5-speed automatic available with the V6.