Last year GM introduced a “mild hybrid” variant of the Saturn Aura sedan. A relatively simple hybrid powertrain improved fuel economy by a couple miles per gallon on the EPA cycle compared to the regular four-cylinder. Not much of a gain, but then GM only charged $2,400 more for the “Green Line” version of the Aura. And this extra cash included alloy wheels, stability control, automatic climate control, and a $1,300 tax credit. TrueDelta calculated an apples-to-apples price bump of about $200.

Not much of a bump. But then the regular 2008 Aura has a $1,250 rebate currently (and had a $2,000 rebate earlier in the month).

These rebates kick the price difference up to $1,500+, and might explain why the Green Line has sold poorly. How poorly? A mere 30 were sold in June.

For 2009, GM adds a six-speed automatic and stability control to the base Aura, and bumps its price by $1,600 (over last year’s intro price) in the process. The new transmission does make the EPA highway rating nearly the same as the hybrid’s. The Green Line gets no new standard equipment other than one-inch-larger alloys and a new name–it’s simply the Aura Hybrid now. The new tires must have very low rolling resistance, as both city and highway EPA ratings are up by two, to 26/34. Overall, these are minor changes. And yet, the base price is up by a whopping $2,790.

Even with today’s gas prices, I don’t see more than a handful of people paying about $2,500 (after adjusting for feature differences) for a four mile-per-gallon improvement in city driving, and a miniscule improvement in highway driving. How did GM’s beancounters figure they could get away with such an increase? Beats me, unless they think discarding “Green Line” in favor of “Hybrid” will ignite interest in the car.

Note: The Malibu Hybrid has received a similar price increase.