The M4 Motorway is the key piece of transport infrastructure in Western Sydney. It is an urban expressway of 40kms, connecting Concord with Penrith. There are 16 major interchanges along the route, including a connection to the Westlink M7 at Eastern Creek.

The M4 provides uninterrupted travel at variable expressway speeds and bypasses 60 sets of traffic lights. It services the transport needs of over 100,000 commuters, local residents and businesses each day, as Sydney's western gateway.

Statewide Roads operates and maintains 2 sections of the Motorway, a 2.5km section between Silverwater Road and James Ruse Drive at Auburn, and a 10km section between May's Hill and Prospect. The RTA operates the remainder of the M4.

The toll plaza at Auburn accepts cash and electronic tags. There are two non-stop electronic tag lanes in each direction.