(In Oct. 9 story, company corrects in last paragraph that Apple's Siri was previously offered on the Chevy Sonic and Spark cars instead of the Cruze and Sonic)
By Ben Klayman
PLYMOUTH, Mich. Oct 9 (Reuters) - General Motors Co is taking the unusual step of offering a mildly restyled version of the Chevrolet Malibu in an effort to reverse the last 18 months of disappointing sales since the mid-sized sedan's last major redesign in early 2012.
The 2014 Malibu, hitting dealer showrooms now, was reworked to improve fuel efficiency and interior space, update the styling and add more technology and a new base 2.5-liter engine.
Analysts say the move is intended to halt GM's slide in the U.S. auto market's largest and most hotly contested sector.
The 2014 model also will be backed by a marketing campaign on par with last year's launch, another unusual move for the No. 1 U.S. automaker.
"They stumbled and they created some of their own problems in 2012 with the Malibu launch, and then when the car came out it was not best-in-class," auto analyst Maryann Keller said.
"They realized they couldn't keep that car as it was on the market in a very, very competitive segment," she added.
The redesigned 2013 Malibu was introduced in limited numbers and in a hybrid version in February 2012. More varieties and different engine options did not arrive in greater quantities until later in the year.
Automakers typically wait at least two years before refreshing a car design.
"We recognize the importance of this segment and how we needed to make sure we were as competitive as possible," Chris Perry, vice president of Chevy marketing in North America, told reporters at an event here. "Eighteen months into it, we recognized that we needed to up our game."
Perry said the refreshed Malibu design was required by the competitiveness of the market, and GM would do it again in other segments if required. He said it would be wrong to call the launch of the 2013 Malibu a failure.
Mid-sized cars make up about 15 percent of the overall U.S. market and the Malibu ranks fifth in sales with 8.2 percent of the market so far this year, according to research firm Kelley Blue Book.
Toyota Motor Corp's Camry led the segment with a 16.8 percent share, followed by Honda Motor Co's Accord at 14.9 percent, Nissan Motor Co's Altima at 13.2 percent, and Ford Motor Co's Fusion at 12 percent, according to KBB.
Malibu's U.S. sales last year rose 3 percent to almost 211,000 vehicles, but so far this year sales are down about 13 percent.
Total industry midsize sales are up 1.5 percent this year, according to KBB. While Toyota's gain in that period matches the segment's, Fusion (up 17 percent), Accord (up 14 percent) and Altima (up 7 percent) have all shown strong gains, according to research firm Autodata.
Fusion, Accord and Altima also were redesigned last year.
Perry said GM is spending about as much as it did to launch the redesigned 2013 model last year, although he declined to quantify that total.
"We're looking at this as an all-new launch," he said.
GM spent $226 million advertising the Malibu in the United States last year, according to WPP Plc unit Kantar Media, which tracks such spending.
The automaker boosted the 2014 Malibu's fuel efficiency by 3 miles per gallon to 25 in the city and by 2 mpg to 36 on the highway with the new base engine. GM said that tops the performance of Ford's Fusion and Toyota's Camry.
The 2014 Malibu, which starts at almost $23,000, in place of last year's hybrid eAssist engine now features stop-start engine technology that saves fuel by allowing the car's engine to shut off when the vehicle is at rest and restart when the accelerator is pressed.
The car also enables incoming texts on the driver's smartphones to be converted to speech and read over the car's audio system, a first for the segment according to GM.
The automaker also added on the 2014 Malibu Apple's "Siri" personal assistant feature at the push of a button, something previously only offered on the Chevy Sonic and Spark cars. (Editing by Xavier Briand)