For eco-conscious buyers there's also the Green Line model, which brings the 2.4L four-cylinder engine rated at 164 horsepower and combined with a motor/generator hybrid system and four-speed automatic. The Green Line model's hybrid system is a so-called "mild hybrid" system, meaning that it can't propel the vehicle on electric power alone but the electric motor system helps the gasoline engine to operate more efficiently by boosting power, allowing it to shut off when idling and decelerating, and saving energy lost in braking within an advanced nickel-metal-hydride battery.
With the four-cylinder engine, the Aura gets 22 mpg city, 30 mpg highway in the EPA cycle; the Green Line does even better, with an estimated 24 mpg city, 32 mpg highway.
The Aura has a distinct appearance inside and out, with LED taillamps that allow extra visibility and safety, detailed, jewel-like headlamps, and a radio antenna built into the rear window. Body-color door handles and power folding side mirrors come on even the cheapest XE-4 model.
With a relatively long wheelbase and stiff chassis, the Aura allows a roomy interior, and suspension tuning oriented toward crisp, sporty handling without sacrificing ride comfort. XE four-cylinder and Green Line models have an electric power steering system, while V6 models get a hydraulic system.
Inside, too, the Aura is better detailed than is expected from a value-priced mid-size sedan. The gauge cluster uses amber-glow LEDs for instrument-panel lighting and a warm tone. XE and XR models now include a Driver Information Center, with real-time fuel economy.
The Aura includes a long list of standard safety features, including four-wheel anti-lock disc brakes, front seat-mounted thorax air bags, and head-curtain side-impact air bags. The StabiliTrak electronic stability control system is standard on all models except the XE four-cylinder.
The XE model, whether equipped with the four-cylinder or V6 engine, comes with tilt/telescoping steering, a 60/40 split folding back seat, cruise control, remote keyless entry, air conditioning, and a six-speaker CD/MP3 sound system. From the XE, the Green Line--in addition to its hybrid powertrain--upgrades to machined alloy wheels, automatic climate control and special instrumentation.
At the top of the line, the XR adds many luxury features including front heated seats, a power driver's seat, steering-wheel mounted audio controls, leather trim, a remote vehicle starter, a universal garage door opener, and an eight-speaker, 240-watt sound system with six-disc changer rear audio controls, and wireless headphones. Major options include leather seating, woodgrain trim, a power sunroof, embossed seat inserts, and adjustable pedals. One year of OnStar Safe & Sound service and a three-month trial service to XM satellite radio are included across the line.