Topping even the very bullish ACT North American Commercial Vehicle Outlook thatACT Research Co. (ACT) released just eight days ago, today ACTannounced that its latest outlook report shows that net orders for North American heavy-duty commercial net orders have reached their “highest level in four- and- a-half years.”

ACT data shows that December net orders for heavy-duty Class 8 commercial vehicles in North America topped 27,044 units—marking a 125% jump year-over-year and the highest monthly total since May, 2006.

What’s more, full-year 2010 production of Class 8 vehicles rose 30% to 154,290 units over “a very weak” 2009.

But medium-duty (Classes 5-7) net orders fell 9% month-over-month from November. However, those orders were up 89% on a year-over-year basis.

“Unlike previous cycles that have been dominated by the U.S., there is a greater breadth of geographic demand for Class 8 equipment this time,” said Kenny Vieth, ACT president & senior analyst.

“While U.S. demand is ramping nicely, orders bound for Canada, Mexico and non-NAFTA export markets remain at healthy level,” he added.

In the outlook report it issued last week, ACT stated it forecasts that heavy-truck demand “will continue to ramp up over the next two years, with production in 2012 and 2013 exceeding 300,000 units.”

“The biggest constraint in 2011 will be the ability of equipment manufacturers and component parts suppliers to ramp up production fast enough [to meet OEM demand],” Vieth noted last week. “As a result, the [new vehicle sales] upcycle is expected to last through 2013.”.

ACT publishes new and used commercial vehicle industry data, market analysis and forecasting services for the North American market as well as the China market.