A trend is a generalization and those don't always apply to particular businesses in every instance. A prevailing nationwide trend may be felt in CA but less in FLA, for example.
We have to address the customers' needs. The need is there. People wash their bodies, clothes and autos. People like to feel sanitary and fresh, not scuzzy and unclean. What about that trend which has been established firmly since indoor plumbing was popularized?
Yes people are cutting back, but they are still driving, going on dates, to weddings, family reunions, driving clients around etc.
If car counts and revenues are down, it's easy to blame a trend. It's harder to get creative, determine the customer needs and if they are changing, adapt your business to a tighter economy and 'go out for business'. Offer value and make it easy for the customer to spend $ at your business and satisfy their need.