Woot offers Sun Joe SPX-FCS1G-CRM Premium Snow Foam Orange-Vanilla Scent Car Wash Soap & Cleaner, 1 Gallon for $12.99 (orig. $39.99).  Free shipping for Prime Members.

Product Description:
FIGHT DIRTY. Give your auto cleaning blast a boost with the NEW sweet scent of ORANGE-VANILLA! This fast-foaming, high-viscosity snow foam auto wash is specially formulated to capture and gently rinse away dirt particles on your vehicle’s exterior to leave behind a superior shine. Gentle on paintwork, tough on road grime. For best results, use with a pressure washer foam cannon attachment (SUN JOE SPX-FC34) for maximum foaming action, and rinse to reveal a clean, brilliant finish. Made for use with pressure washers. 

• [CONCENTRATE]: Pressure washer concentrate formula
• [SAFE]: Biodegradable, safe on metal surfaces
• [DEEP CLEANING]: Removes dirt and grime, yet safe for wax and sealants
• [VERSATILE]: Can be applied with a mop or brush to clean wood, brick and more.
• [BEST RESULTS]: For best results, use with a pressure washer foam cannon attachment (Sun Joe SPX-FC34)