With some models, like this Chevrolet Equinox, posting triple-digit sales gains, General Motors is boosting production. And other makers, including Ford and Toyota are following, GM's lead.

Stronger sales have prompted General Motors Company to push forward plans to boost production.  (See General Motor’s March Sales up 21%)

The latest signal came this week when GM announced plans to add 100 workers at a transmission plant in Warren, Michigan, which is used for building the six-speed automatic gearbox used in vehicles such as the Chevrolet Equinox, Traverse, Malibu and Impala, Buick LaCrosse, Enclave and Lucerne and GMC Acadia and Terrain.

Through the first three months of the year, U.S. sales for Equinox have risen 130%, compared to the same period last year.  LaCrosse sales are up 197% and Terrain sales are up 245%, compared to the vehicle it replaced, the Pontiac Torrent.

Overall GM’s sales increased 20% but that number is misleading, since it doesn’t account for the fact that the maker has abandoned four brands since emerging from bankruptcy, last year.  Sales at its surviving, core brands, Chevrolet, Buick, Cadillac and GMC, soared 43% in March.

Susan Docherty, GM’s vice president of marketing, contends the 43% increase demonstrates that the company’s turnaround plan was working.  If nothing else, it means that the maker needs to respond where demand is now exceeding supply.

GM has added a third shift and overtime at company passenger car assembly plant in Fairfax, Kansas, to keep up with the consumer purchases of the Chevrolet Malibu and Buick Lacrosse. GM also is adding a third shift at the company’s assembly plant in Delta Township near Lansing, Michigan, Docherty said.

“We’re also adding overtime at the plant that builds the Camaro, noted Jim Campbell, U.S. vice president of marketing for the Chevrolet division.  Campbell noted GM is meanwhile stepping up production of the Chevrolet Equinox by trucking bodies from the plant in Ingersoll, Ontario to the assembly complex in nearby Oshawa, Ontario. where the bodies will be painted and finished.

GM initially hesitated before approving production increases.  Like its competitors, the maker wanted to be sure demand would stay high and that the economy wouldn’t suffer the double-dip recession some economists had been forecasting.  With that possibility seeming increasingly unlikely – and with car sales running at above expectations – the maker has been giving the go to its production planners.

But GM isn’t alone.  Ford, Toyota and Chrysler also have announced production increases on key products, and observers believe still more could follow if the pace of car sales continues to hold.

Paul Taylor, chief economist with the National Automobile Dealers Association, said increasing sales of new vehicles during March and the first quarter show that the overall outlook for the car industry appear to have improved.

“The March data shows a welcome increase in new-car sales,” Taylor said, adding that, “April new-car sales will provide an indication of what the economy will support without intervening factors, such as ‘catch-up’ sales.”

Other analysts have said that after reviewing the March sales data, which included major double digit increases for almost every single manufacturer, the auto industry appears ready for a slow but steady recovery.