A WardsAuto analysis of North American light-vehicle capacity utilization shows the best results are coming from auto makers employing 3-crew or 3-shift operations at their assembly plants.

This is a major reason why utilization rates currently are at extreme highs.

The third quarter’s North American LV utilization rate of 93.5% was the best for the period since WardsAuto began tracking the data in 2005. It followed the second quarter’s 100.1%, which marked the second-best result on record for the period and the first time the rate reached the 100% level in the past seven years.

With fourth-quarter North American production forecast to rise 8.3% from year-ago, pending fallout from Superstorm Sandy, capacity utilization of 93.1% in the final three months of 2012 also will be a period high.

Capacity utilization for all of 2012 is forecast at 96.5%, rising to 96.7% in 2013, including rates of more than 100% in the first and second quarters.

Nissan, which just added third shifts to its Canton, MS, and Smyrna, TN, facilities, will end 2012 at 112.5% capacity utilization, the highest rate among the region’s six biggest volume manufacturers. Ford, which has six plants running three crews/shifts, is forecast to finish the year at 109.9%.

The capacity utilization rate for rest of the top six is Chrysler (94.4%), Honda (92.0%), Toyota (88.7%) and General Motors (86.2%). Of the four, two have plants on 3-crew/shift systems and are planning to add more.

Chrysler in July added a third crew at its Belvidere, IL, location, and will do the same in the fourth quarter at its Detroit-Jefferson North plant. It also is considering adding a third shift next year at its Dodge City Ram pickup facility in Warren, MI.

GM has seven plants running three crews/shifts and will add Arlington, TX, to the list in first-quarter 2013. WardsAuto also expects the auto maker to add a third shift by the third quarter at its Oshawa 1 plant in Ontario, Canada. The facility builds the Chevrolet Camaro and Cadillac XTS and will launch production of the redesigned ’14 Chevrolet Impala early next year.

Volkswagen, which is forecast to reach 145.1% capacity utilization in 2012, will add a third crew to its Chattanooga, TN, plant in December. It already assembles cars on three shifts in Puebla, Mexico.

Including medium- and heavy-duty trucks, the North American third-quarter capacity utilization rate was 92.7%, compared with 78.7% in like-2011. Through September, the rate was 97.0%, compared with 81.5% year-ago.