If there is no grassy area nearby, consider using a commercial car wash that treats or recycles its wastewater.
Use mild detergents, and never clean or pressure wash the undercarriage of a car at home. The oil, grease and other pollutants from this activity can contaminate shallow groundwater.
Always use a hose nozzle with a trigger, and shut it off when you’re not using it to conserve water.
Store automotive parts, such as batteries, engines, transmissions, and other parts that may have oily or greasy residue on them, under cover and off the ground, to minimize rainwater contact. Rainwater can wash pollutants off these parts and into stormdrains.
Repair leaks and dispose of used auto fluids and batteries at designated drop-off or recycling locations.