In Pixar's Cars, the green hippie Volkswagen bus is Fillmore.
Fillmore is a resident of Radiator Springs and the town's advocate for organic fuel. His design is based on the classic Volkswagen Type 2 microbus, a vehicle strongly associated with the 1960s and counterculture. He runs Fillmore's Organic Fuel and regularly disagrees with Sarge, the military-themed jeep who lives next door.
The character's name is a reference to the Fillmore music venues and the San Francisco neighborhood associated with music and counterculture. Sarge is the green military jeep, Ramone is the lowrider who operates Ramone's House of Body Art, and Red is the town's shy fire truck. Those visual details can cause confusion, but the hippie Volkswagen bus is specifically Fillmore.