A versatile portable car wash should support dual water sources: a direct tap connection and a self-priming function (drawing water from a bucket or lake). This is critical for 'portable' use cases. The design should include a multi-function nozzle (0°, 15°, 25°, 40°, and foam mode) to handle different tasks, from removing heavy mud to gentle rinsing and soap application. For B2B buyers, offering modular attachments like long brushes or undercarriage cleaners can significantly increase the product's market value.