Treated the ol' girl to a wash yesterday at the local self-serve spot. I'd have hand-washed her, but I'm in the middle of a major move/life change so I went for the closest alternative.
Given the state of exterior on my particular example, I had no qualms about utilizing the foamy brush to scrub off some of the more stubborn mud and road grime. However, water leakage IS a concern. Early on, I became aware of very slight leaks at the top front corners of both the driver's and passenger's door windows when faced with high-pressure water or steady rainfall. The self-serve allowed me to control the volume/pressure of water directed towards the top of the windows. Low and behold: I found zero water droplets on the door panels afterwards.
Of lesser note: fuel economy. To date, she's been treated to a fresh set of 225/60R16 Kumho LX Plat's, a set of NGK TR55's backed by ACD wires, a new accessory belt, and a fresh 10W30 oil change. Having owned several 3800 powered vehicles in the past (both NA and SC), I expected somewhere in the 19-21 MPG range. To my surprise, the math reported 22.3!