A torched stolen car has sparked a grassfire in NSW's Central West, forcing the closure of a highway as the blaze was doused.

Police said officers were driving along the Newell Highway about 16km north of Parkes at about 10:40pm (AEDT) on Tuesday when they came across a silver Honda Accord on fire.

They tried to put out the fire but it spread to nearby grass, shrubs and trees, burning through two hectares.

The Newell Highway was closed as Rural Fire Service volunteers and local landowners extinguished the fire.

Police said the 1991 model Honda was stolen from Dubbo at about 5pm on Tuesday and have urged anyone with information on the theft to call Crime Stoppers on 1800 333 000.

The torching comes as firefighters battle more than 140 bush and grassfires across the state and authorities warn that deliberately lit fires threaten lives and property.