You don’t know enough people, then. There are a lot of environmentally conscious people who would absolutely first think “because it is close we should walk” and then follow up with the logical conclusion that you can’t walk to wash your car. Many people communicate by sharing their thinking process, I can think of many people who would share their ideology as it pertains to a question like this. A pragmatic environmentalist (hopefully that is all of them) would know that their ideology isn’t consequential but could certainly mention it. After all, you may need to drive your car to the car wash to wash it, but do you need to wash it? Are the chemicals used by the car wash harmful? Are there better ways to keep a car maintained?