General Motors Co.’s second-half production schedule is showing an upward trendline with the addition of 60,000 vehicles to its third- and fourth-quarter forecasts.

Demand for fuel-efficient vehicles prompted the move, which affects some 1,350 hourly workers and boosts output of the Chevrolet Cobalt small car and Equinox midsize cross-utility vehicle and all-new GMC Terrain midsize CUV.

“During the third-quarter 2009, we’ve added production which will result in 35% increase over the second quarter,” says Mark LaNeve, vice president-U.S. sales.

“With today’s announcement of further additions, the fourth quarter will now be at least 20% higher than the third quarter, which is a very positive trend.”

The Cobalt is assembled at GM’s plant in Lordstown, OH, and the CUVs are produced at CAMI Automotive Inc., the auto maker’s joint venture with American Suzuki Motor Corp., in Ingersoll, ON, Canada.

The website for United Auto Workers Local 1112, which represents Lordstown assemblers, says a second shift will be added to the Ohio plant effective Oct. 5.

Meanwhile, an internal memo from CAMI President Robert Parcell targets an Oct. 19 return to 3-shift production, but Mike VanBoekel, president of Canadian Auto Workers Local 88 that represents CAMI assemblers, suggests the increase could occur as early as mid-September.

“The lines are already humming now on two (shifts),” VanBoekel tells Ward’s.

The reason? The Equinox is high on the lists of shoppers lured to showrooms by “Cash-for-Clunkers” legislation.

The CUV’s 2.4L 4-cyl. engine “is what they want,” says Matt Poniatowski, Internet sales manager at Matthews-Hargreaves Chevrolet Co. in Royal Oak, MI.

As of July 31, GM was down to a 25 days’ supply of the Equinox, according to Ward’s data. The Terrain is just ramping up. Days’ supply for the Cobalt was at 70.

Demand also is high for the Chevy Colorado and GMC Canyon small pickups, as well as the Chevy HHR CUV, GM claims. And the auto maker says it anticipates the need to bump up production of the Chevy Camaro muscle coupe, Cadillac SRX CUV, CTS Wagon and Buick Lacrosse D-segment car.

“We are running our plants to maintain maximum flexibility and keep production tightly aligned with customer demand,” says Tim Lee, GM group vice president, global manufacturing and labor.

“The uptick is an encouraging sign that vehicle sales are turning around, and we will ramp up quickly to meet that demand.”