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Being a standard GM rig, the Aura Hybrid's stereo also comes with a generic auxiliary-input jack to enable drivers to connect iPods and other portable MP3 players when on the road. On the downside, there is no means of upgrading the Aura's factory-installed audio capabilities, and the car comes without any option for satellite radio--a curious omission, seeing as we've seen XM in many other GM models with the same basic stereo infrastructure. With its six speakers, the Aura Green Line's audio system sounds adequate at low-to-mid volume, but starts to distort at higher volumes, particularly at the low end of the acoustic range.
Aside from the mirror-mounted OnStar interface detailed above, the only other notable tech features of the Aura Hybrid's cabin are its three hybrid-related instrument gauges. On the right-hand side of the instrument cluster, the assist/charge meter indicates the status of the battery, and whether it is being used to assist the engine (a swing of the needle upwards), whether it is being charged up by the regenerative braking system (downward swing) or whether there is no engine-battery exchange. On the left of the instrument cluster, the Aura's Autostop gauge indicates when the car's gasoline engine is cut during idling. Finally, a green backlit ECO fuel economy indicator illumines when the car is meeting or exceeding its average EPA fuel economy. For more details on these systems, see the Under the Hood section below.
As with the 2007 Saturn Vue Green Line, the Aura Green Line's air-conditioning system has a hybrid setting that allows it to be powered either from the battery or directly from the engine. With the A/C set to a temperature of 65 degrees or above, the system can be run on electric only, enabling the Autostop function to kick in when the car is idling. With the air conditioning set to 60 degrees, however, the A/C motor requires additional propulsion from the engine, preventing the Autostop function from activating.
Under the hood
Saturn's cut-price hybrid relies on cut-price technology. The Aura Green Line does have an electric motor, powered by its onboard nickel metal hydride (NiMH) battery pack, but as this is a "mild" rather than "full" hybrid, the car cannot be driven in elecric-only mode like some "full" hybrids. As with the Vue Green Line, the Aura Green Line relies on a system called Belt Alternator Starter (BAS), which replaces the car's alternator with an electric motor. This motor can be used either to assist the 2.4-liter gasoline engine when accelerating from standing and with increased load demand, or to charge the battery by turning the car's braking and deceleration into electricity.
The BAS system is also able to shut off the engine for up to 2 minutes during idling (Autostop) and to cut off the fuel supply during deceleration. All electrical systems in the Aura Green Line, including the air-conditioning and stereo, run on a 48-volt system connected directly to the battery pack, and can therefore still be operated during the Autostop mode.
In practice, the Aura Green Line feels underpowered for its size, even with the electric boost from the battery. Flooring the gas pedal on the freeway results in a bleat from the engine and some movement in the charge/assist gauge, but very little in the way of throttle response. On the positive side, the Aura Green Line's regenerative braking system is much less intrusive and provides a far more linear braking experience than those in the Mercury Mariner and Ford Escape hybrids.
Around the city, the Aura Green Line feels soft and flaccid in cornering, demonstrating predictable understeer, while on the freeway, it cruises along comfortably provided it is not required to perform any sudden bursts of acceleration. In freeway driving we also noticed a commendable level of cabin damping, with very little road or wind noise getting in. Despite its entry-level technology, the BAS hybrid system does offer significantly improved fuel economy over the gasoline-only Aura. In our 250 miles of driving, we observed an average fuel economy of 26 mpg: significantly better than the 20 mpg that we observed in the Aura XR, and in line with the EPA's updated estimates for the car of 24 mpg city/32 highway.
Our 2007 Saturn Aura Green Line test car came with a base price of $22,045. To this we added the only available factory option in the form of the $375 Preferred Package, which gave us power-adjustable seats, steering wheel audio controls, and folding power outside mirrors. Including a $650 destination fee, the final sticker price of our test car was $23,070, making it cheaper by some margin than the Honda Civic Hybrid, particularly with the Aura's $1,300 Federal tax credit. The Saturn Aura Green Line generally fulfills its mission of being a stripped-down, entry-level hybrid. Those looking for LCDs showing the intricate workings of complex hybrid systems should keep driving to the Toyota dealer: those looking for a no frills sedan that gets more than 25 mpg for less than $25,000 should consider the Aura Green Line.