Elbow grease is more virtuous than a mechanical scrubdown.
A DIY wash may show your wheels some love; the environment, not so much. And water use—about 100 gallons per ten minutes of home washing, 45 gallons total for a pro car wash—isn't the only factor to consider. At home the motor oil, gasoline, and other chemical grit that's gunking up your car's underbelly can run off into sewer drains, which empty into waterways, potentially suffocating fish. Car washes, by contrast, have to follow wastewater regulations, so the water is filtered and cleaned before it reaches streams and ponds.
Try new car wash products like Eco Touch Waterless Car Wash.